V2X transmission resource selecting method implemented by terminal in wireless communication system and terminal using same

ABSTRACT

Disclosed are a V2X (vehicle-to-everything) transmission resource selecting method implemented by a terminal in a wireless communication system and a terminal using the method. The method is characterized by: receiving type information for indicating the type of a resource pool; and executing a resource selection, on the basis of partial sensing, and/or a random selection from the resource pool on the basis of the type information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2017/002413, filed on Mar. 6, 2017,which claims the benefit of U.S. Provisional Applications No. 62/303,389filed on Mar. 4, 2016, No. 62/316,574 filed on Apr. 1, 2016, No.62/321,748 filed on Apr. 13, 2016, No. 62/333,862 filed on May 10, 2016,No. 62/350,727 filed on Jun. 16, 2016, No. 62/379,221 filed on Aug. 24,2016, No. 62/401,743 filed on Sep. 29, 2016, No. 62/403,028 filed onSep. 30, 2016, No. 62/416,669 filed on Nov. 2, 2016, and No. 62/423,738filed on Nov. 17, 2016, the contents of which are all herebyincorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to wireless communication and, mostparticularly, to a V2X transmission resource selecting methodimplemented by a terminal in a wireless communication system and aterminal using the same.

Related Art

In International Telecommunication Union Radio communication sector(ITU-R), a standardization task for International MobileTelecommunication (IMT)-Advanced, that is, the next-generation mobilecommunication system since the third generation, is in progress.IMT-Advanced sets its goal to support Internet Protocol (IP)-basedmultimedia services at a data transfer rate of 1 Gbps in the stop andslow-speed moving state and of 100 Mbps in the fast-speed moving state.

For example, 3^(rd) Generation Partnership Project (3GPP) is a systemstandard to satisfy the requirements of IMT-Advanced and is preparingfor LTE-Advanced improved from Long Term Evolution (LTE) based onOrthogonal Frequency Division Multiple Access (OFDMA)/SingleCarrier-Frequency Division Multiple Access (SC-FDMA) transmissionschemes. LTE-Advanced is one of strong candidates for IMT-Advanced.

There is a growing interest in a Device-to-Device (D22) technology inwhich devices perform direct communication. In particular, D2D has beenin the spotlight as a communication technology for a public safetynetwork. A commercial communication network is rapidly changing to LTE,but the current public safety network is basically based on the 2Gtechnology in terms of a collision problem with existing communicationstandards and a cost. Such a technology gap and a need for improvedservices are leading to efforts to improve the public safety network.

The public safety network has higher service requirements (reliabilityand security) than the commercial communication network. In particular,if coverage of cellular communication is not affected or available, thepublic safety network also requires direct communication betweendevices, that is, D2D operation.

D2D operation may have various advantages in that it is communicationbetween devices in proximity. For example, D2D UE has a high transferrate and a low delay and may perform data communication. Furthermore, inD2D operation, traffic concentrated on a base station can bedistributed. If D2D UE plays the role of a relay, it may also play therole of extending coverage of a base station.

The above-described D2D communication may be expanded and applied tosignal transmission and/or reception between vehicles. Mostparticularly, vehicle-related communication is referred to asvehicle-to-everything (V2X) communication.

In V2X, the term ‘X’ refers to a pedestrian (communication between avehicle and a device carried by an individual (e.g.: handheld terminalcarried by a pedestrian, cyclist, driver or passenger), in this case,V2X may be indicated V2P), a vehicle (communication between vehicles)(V2V), an infrastructure/network (communication between a vehicle and aroadside unit (RSU)/network (e.g., RSU is a transportationinfrastructure entity (e.g., an entity transmitting speed notifications)implemented in an eNB or a stationary UE)) (V2I/N), and so on.

A (V2P communication related) device that is carried by a pedestrian (orindividual) will be referred to as a “P-UE”, and a (V2P communicationrelated) device that is installed in a vehicle will be referred to as a“V-UE”. In the present invention, the term ‘entity’ may be interpretedas at least one of a P-UE, V-UE, RSU(/network/infrastructure).

Meanwhile, in the V2X communication, when the P-UE intends to transmit av2X signal, how to select which resource may be an issue. Unlike adevice that is installed in a vehicle, the P-UE is sensitive to batterypower consumption. Additionally, important issues in the V2Xcommunication may also correspond to periodically transmitting signalsand not causing interference to other devices (or terminals).Accordingly, a method for selecting transmission resources of a P-UEwhile considering the above-mentioned important issues needs to bedetermined.

SUMMARY OF THE INVENTION

A technical object that is to be achieved by the present invention is toprovide a V2X transmission resource selecting method implemented by aterminal in a wireless communication system and a terminal using thesame.

In one aspect, provided is a method of selecting a vehicle-to-everything(V2X) transmission resource performed by a user equipment (UE). Themethod includes receiving type information indicating a type of aresource pool and performing at least one of random selection andpartial sensing based resource selection in the corresponding resourcepool based on the received type information.

The type information may indicate whether partial sensing is allowed tobe performed when the UE performs resource selection in thecorresponding resource pool, and the type information may indicatewhether random selection is allowed to be performed when the UE performsresource selection in the corresponding resource pool.

The partial sensing may correspond to a sensing method selecting onlysome subframes, among subframes existing in a sensing window, andselecting a specific subframe within a selecting window as a V2Xtransmission subframe based on the sensing result.

The sensing window may be configured of 1,000 consecutive subframes, andwherein the selecting window is configured of 100 consecutive subframespositioned after the sensing window.

In case the type of the resource pool corresponds to a type in whichonly the partial sensing based resource selection is allowed to beperformed, the UE may semi-persistently reserve the resource that isselected by performing the partial sensing based resource selection.

In case the type of the resource pool corresponds to a type in whichonly the random selection is allowed to be performed, the UE may notsemi-persistently reserve the resource that is selected by performingthe random selection.

In case the type of the resource pool corresponds to a type in which thepartial sensing based resource selection is allowed to be performed, andin case the UE performs random selection in the corresponding resourcepool, the UE may semi-persistently reserve the randomly selectedresource.

The UE may be a UE communicating with another UE being installed in avehicle.

In another aspect, provided is a user equipment (UE). The UE includes aradio frequency (RF) unit transmitting and receiving radio signals and aprocessor being operatively connected to the RF unit. The processor isconfigured to receive type information indicating a type of a resourcepool, and to perform at least one of random selection and partialsensing based resource selection in the corresponding resource poolbased on the received type information.

According to the present invention, the network may notify (or indicateto) a pedestrian UE of the resource pool type, i.e., whether only randomselection is allowed to be performed, or whether only partial sensingbased resource selection is allowed to be performed, or whether bothrandom selection and partial sensing based resource selection areallowed to be performed, when selecting a resource than can transmit aV2X signal. Since the pedestrian UE performs adequate operations inaccordance with the resource pool type, interference caused to other UEsmay be reduced. Additionally, in case different types of resource poolsoverlap, the UE regulates the method according to which it operates. Forexample, when a UE performs random selection in a resource pool, whereinthe partial sensing based resource selection is allowed to be performed,unlike the operations that are performed in the resource pool, whereinonly the random selection is allowed, the corresponding UE maysemi-persistently reserve the randomly selected resource during apredetermined period of time and may then perform the operations thatare adequate to the characteristics of the resource pool, wherein thepartial sensing based resource selection is allowed to be performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system to which the presentinvention can be applied.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane.

FIG. 3 is a diagram showing a wireless protocol architecture for acontrol plane.

FIG. 4 shows a basic structure for ProSe.

FIG. 5 shows the deployment examples of types of UE performing ProSedirect communication and cell coverage.

FIG. 6 shows a user plane wireless protocol stack for a ProSe directcommunication.

FIG. 7 shows a PC5 interface for a D2D discovery.

FIG. 8 is an example of an LTE SL V2V detection signal using timerepetition of a short sequence.

FIG. 9 is an example of an LTE SL V2V detection signal using sequencematching in the frequency domain.

FIG. 10 is an example of a V2X transmission resource selecting methodaccording to a partial sensing operation of <Proposed Method #2>.

FIG. 11 is an example of a V2X transmission subframe determining methodaccording to the <Proposed Method #2>.

FIG. 12 is an example of a communication method between a pedestrian UE(P-UE), a vehicle UE (V-UE), and a network according to the <ProposedMethod #2>.

FIG. 13 shows an example of a method for selecting a V2X transmissionresource according to Example #4-1.

FIG. 14 shows an example of a method for selecting a V2X transmissionresource according to Example #4-1.

FIG. 15 shows an example of the V2X transmission resource pool types.

FIG. 16 is an example of a method for selecting a V2X resource pool in asituation where multiple types of resource pools exist.

FIG. 17 shows an exemplary operation of a UE that has selected aresource by using the random selection method within a resource poolwherein the (partial) sensing is allowed.

FIG. 18 is a flow chart showing a method for transmitting a V2X messageperformed by a UE having a limited reception capability according to anexemplary embodiment of the present invention.

FIG. 19 is a flow chart showing a method for transmitting a V2X messageperformed by a UE having a limited reception capability according toanother exemplary embodiment of the present invention.

FIG. 20 is a flow chart showing a method for transmitting a V2X messageperformed by a UE having a limited reception capability according to yetanother exemplary embodiment of the present invention.

FIG. 21 is a flow chart of a V2X transmission method, in a case where aWAN transmission operation overlaps with a V2X transmission operation ina time domain, according to an exemplary embodiment of the presentinvention.

FIG. 22 shows a general example, wherein the V2X transmission operationand the WAN (UL) transmission operation each being performed within adifferent carrier (partially or fully) overlap one another in the timedomain.

FIG. 23 is a flow chart of a V2X transmission method, in a case where aWAN transmission operation overlaps with a V2X transmission operation ina time domain, according to another exemplary embodiment of the presentinvention.

FIG. 24 shows a general example, wherein the V2X transmission operation(overlapping with the WAN (UL) transmission operation within the samecarrier (and/or different carriers) in the time domain) is prioritizedover the WAN (UL) transmission.

FIG. 25 is a flow chart of a V2X transmission method, in a case where aWAN transmission operation overlaps with a V2X transmission operation ina time domain, according to yet another exemplary embodiment of thepresent invention.

FIG. 26 is a block diagram showing a user equipment (UE) implementing anexemplary embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows a wireless communication system to which the presentinvention can be applied. The wireless communication system may bereferred to as an Evolved-UMTS Terrestrial Radio Access Network(E-UTRAN) or a Long Term Evolution (LTE)/LTE-A system, for example.

The E-UTRAN includes at least one base station (BS) 20 which provides acontrol plane and a user plane to a user equipment (UE) 10. The UE 10may be fixed or mobile, and may be referred to as another terminology,such as a mobile station (MS), a user terminal (UT), a subscriberstation (SS), a mobile terminal (MT), a wireless device, etc. The BS 20is generally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as an evolved node-B (eNB), abase transceiver system (BTS), an access point, etc.

The BSs 20 are interconnected by means of an X2 interface. The BSs 20are also connected by means of an S1 interface to an evolved packet core(EPC) 30, more specifically, to a mobility management entity (MME)through S1-MME and to a serving gateway (S-GW) through S1-U.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway(P-GW). The MME has access information of the UE or capabilityinformation of the UE, and such information is generally used formobility management of the UE. The S-GW is a gateway having an E-UTRANas an end point. The P-GW is a gateway having a PDN as an end point.

Layers of a radio interface protocol between the UE and the network canbe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. Among them, a physical (PHY) layer belonging to the first layerprovides an information transfer service by using a physical channel,and a radio resource control (RRC) layer belonging to the third layerserves to control a radio resource between the UE and the network. Forthis, the RRC layer exchanges an RRC message between the UE and the BS.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane. FIG. 3 is a diagram showing a wireless protocol architecture fora control plane. The user plane is a protocol stack for user datatransmission. The control plane is a protocol stack for control signaltransmission.

Referring to FIGS. 2 and 3, a PHY layer provides an upper layer with aninformation transfer service through a physical channel. The PHY layeris connected to a medium access control (MAC) layer which is an upperlayer of the PHY layer through a transport channel. Data is transferredbetween the MAC layer and the PHY layer through the transport channel.The transport channel is classified according to how and with whatcharacteristics data is transferred through a radio interface.

Data is moved between different PHY layers, that is, the PHY layers of atransmitter and a receiver, through a physical channel. The physicalchannel may be modulated according to an Orthogonal Frequency DivisionMultiplexing (OFDM) scheme, and use the time and frequency as radioresources.

The functions of the MAC layer include mapping between a logical channeland a transport channel and multiplexing and demultiplexing to atransport block that is provided through a physical channel on thetransport channel of a MAC Service Data Unit (SDU) that belongs to alogical channel. The MAC layer provides service to a Radio Link Control(RLC) layer through the logical channel.

The functions of the RLC layer include the concatenation, segmentation,and reassembly of an RLC SDU. In order to guarantee various types ofQuality of Service (QoS) required by a Radio Bearer (RB), the RLC layerprovides three types of operation mode: Transparent Mode (TM),Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provideserror correction through an Automatic Repeat Request (ARQ).

The RRC layer is defined only on the control plane. The RRC layer isrelated to the configuration, reconfiguration, and release of radiobearers, and is responsible for control of logical channels, transportchannels, and PHY channels. An RB means a logical route that is providedby the first layer (PHY layer) and the second layers (MAC layer, the RLClayer, and the PDCP layer) in order to transfer data between UE and anetwork.

The function of a Packet Data Convergence Protocol (PDCP) layer on theuser plane includes the transfer of user data and header compression andciphering. The function of the PDCP layer on the user plane furtherincludes the transfer and encryption/integrity protection of controlplane data.

What an RB is configured means a process of defining the characteristicsof a wireless protocol layer and channels in order to provide specificservice and configuring each detailed parameter and operating method. AnRB can be divided into two types of a Signaling RB (SRB) and a Data RB(DRB). The SRB is used as a passage through which an RRC message istransmitted on the control plane, and the DRB is used as a passagethrough which user data is transmitted on the user plane.

If RRC connection is established between the RRC layer of UE and the RRClayer of an E-UTRAN, the UE is in the RRC connected state. If not, theUE is in the RRC idle state.

A downlink transport channel through which data is transmitted from anetwork to UE includes a broadcast channel (BCH) through which systeminformation is transmitted and a downlink shared channel (SCH) throughwhich user traffic or control messages are transmitted. Traffic or acontrol message for downlink multicast or broadcast service may betransmitted through the downlink SCH, or may be transmitted through anadditional downlink multicast channel (MCH). Meanwhile, an uplinktransport channel through which data is transmitted from UE to a networkincludes a random access channel (RACH) through which an initial controlmessage is transmitted and an uplink shared channel (SCH) through whichuser traffic or control messages are transmitted.

Logical channels that are placed over the transport channel and that aremapped to the transport channel include a broadcast control channel(BCCH), a paging control channel (PCCH), a common control channel(CCCH), a multicast control channel (MCCH), and a multicast trafficchannel (MTCH).

The physical channel includes several OFDM symbols in the time domainand several subcarriers in the frequency domain. One subframe includes aplurality of OFDM symbols in the time domain. An RB is a resourcesallocation unit, and includes a plurality of OFDM symbols and aplurality of subcarriers. Furthermore, each subframe may use specificsubcarriers of specific OFDM symbols (e.g., the first OFDM symbol) ofthe corresponding subframe for a physical downlink control channel(PDCCH), that is, an L1/L2 control channel. A Transmission Time Interval(TTI) is a unit time for subframe transmission.

Now, the D2D operation will be described. In 3GPP LTE-A, the servicerelated to D2D operation is called proximity based service (ProSe).Hereinafter, ProSe is equivalent to D2D operation and ProSe may beinterchanged with D2D operation. ProSe will now be described.

The ProSe includes ProSe direction communication and ProSe directdiscovery. The ProSe direct communication is communication performedbetween two or more proximate UEs. The UEs may perform communication byusing a protocol of a user plane. A ProSe-enabled UE implies a UEsupporting a procedure related to a requirement of the ProSe. Unlessotherwise specified, the ProSe-enabled UE includes both of a publicsafety UE and a non-public safety UE. The public safety UE is a UEsupporting both of a function specified for a public safety and a ProSeprocedure, and the non-public safety UE is a UE supporting the ProSeprocedure and not supporting the function specified for the publicsafety.

ProSe direct discovery is a process for discovering anotherProSe-enabled UE adjacent to ProSe-enabled UE. In this case, only thecapabilities of the two types of ProSe-enabled UE are used. EPC-levelProSe discovery means a process for determining, by an EPC, whether thetwo types of ProSe-enabled UE are in proximity and notifying the twotypes of ProSe-enabled UE of the proximity.

Hereinafter, for convenience, the ProSe direct communication may bereferred to as D2D communication, and the ProSe direct discovery may bereferred to as D2D discovery.

FIG. 4 shows a basic structure for ProSe.

Referring to FIG. 4, the basic structure for ProSe includes an E-UTRAN,an EPC, a plurality of types of UE including a ProSe applicationprogram, a ProSe application server (a ProSe APP server), and a ProSefunction.

The EPC represents an E-UTRAN core network configuration. The EPC mayinclude an MME, an S-GW, a P-GW, a policy and charging rules function(PCRF), a home subscriber server (HSS) and so on.

The ProSe APP server is a user of a ProSe capability for producing anapplication function. The ProSe APP server may communicate with anapplication program within UE. The application program within UE may usea ProSe capability for producing an application function.

The ProSe function may include at least one of the followings, but isnot necessarily limited thereto.

-   -   Interworking via a reference point toward the 3rd party        applications    -   Authorization and configuration of UE for discovery and direct        communication    -   Enable the functionality of EPC level ProSe discovery    -   ProSe related new subscriber data and handling of data storage,        and also handling of the ProSe identities    -   Security related functionality    -   Provide control towards the EPC for policy related functionality    -   Provide functionality for charging (via or outside of the EPC,        e.g., offline charging)

A reference point and a reference interface in the basic structure forProSe are described below.

-   -   PC1: a reference point between the ProSe application program        within the UE and the ProSe application program within the ProSe        APP server. This is used to define signaling requirements in an        application dimension.    -   PC2: a reference point between the ProSe APP server and the        ProSe function. This is used to define an interaction between        the ProSe APP server and the ProSe function. The update of        application data in the ProSe database of the ProSe function may        be an example of the interaction.    -   PC3: a reference point between the UE and the ProSe function.        This is used to define an interaction between the UE and the        ProSe function. A configuration for ProSe discovery and        communication may be an example of the interaction.    -   PC4: a reference point between the EPC and the ProSe function.        This is used to define an interaction between the EPC and the        ProSe function. The interaction may illustrate the time when a        path for 1:1 communication between types of UE is set up or the        time when ProSe service for real-time session management or        mobility management is authenticated.    -   PC5: a reference point used for using control/user plane for        discovery and communication, relay, and 1:1 communication        between types of UE.    -   PC6: a reference point for using a function, such as ProSe        discovery, between users belonging to different PLMNs.    -   SGi: this may be used to exchange application data and types of        application dimension control information.

<ProSe Direct Communication (D2D Communication)>.

The ProSe direction communication corresponds to a communication modeenabling two common safety devices to perform direct communicationthrough a PC 5 interface. This communication mode may be supported bothin a case when the UEs receive services within a coverage of an E-UTRANand in a case when a UE deviates from the coverage of the E-UTRAN.

FIG. 5 shows the deployment examples of types of UE performing ProSedirect communication and cell coverage.

Referring to FIG. 5(a), types of UE A and B may be placed outside cellcoverage. Referring to FIG. 5(b), UE A may be placed within cellcoverage, and UE B may be placed outside cell coverage. Referring toFIG. 5(c), types of UE A and B may be placed within single cellcoverage. Referring to FIG. 5(d), UE A may be placed within coverage ofa first cell, and UE B may be placed within coverage of a second cell.

ProSe direct communication may be performed between types of UE placedat various positions as in FIG. 5.

Meanwhile, the following IDs may be used in the ProSe directioncommunication.

Source Layer-2 ID: This ID identifies the transmitter of a packet in thePC 5 interface.

Target Layer-2 ID: This ID identifies the target of a packet in the PC 5interface.

SA L1 ID: This ID corresponds to an ID for a scheduling assignment (SA)in the PC 5 interface.

FIG. 6 illustrates a user-plane protocol stack for the ProSe directioncommunication.

Referring to FIG. 6, the PC 5 interface is configured of PDCH, RLC, MAC,and PHY layers.

In the ProSe direct communication, there may be no HARQ feedback. A MACheader may include a Source Layer-2 ID and a Target Layer-2 ID.

<Radio Resource Assignment for ProSe Direct Communication>.

A ProSe-enabled device (or terminal or user equipment (UE)) may use thefollowing 2 modes of resource assignment for the ProSe directioncommunication.

1. Mode 1

Mode 1 is mode in which resources for ProSe direct communication arescheduled by an eNB. UE needs to be in the RRC_CONNECTED state in orderto send data in accordance with mode 1. The UE requests a transmissionresource from an eNB. The eNB performs scheduling assignment andschedules resources for sending data. The UE may send a schedulingrequest to the eNB and send a ProSe Buffer Status Report (BSR). The eNBhas data to be subjected to ProSe direct communication by the UE basedon the ProSe BSR and determines that a resource for transmission isrequired.

2. Mode 2

Mode 2 is mode in which UE directly selects a resource. UE directlyselects a resource for ProSe direct communication in a resource pool.The resource pool may be configured by a network or may have beenpreviously determined.

Meanwhile, if UE has a serving cell, that is, if the UE is in theRRC_CONNECTED state with an eNB or is placed in a specific cell in theRRC_IDLE state, the UE is considered to be placed within coverage of theeNB.

If UE is placed outside coverage, only mode 2 may be applied. If the UEis placed within the coverage, the UE may use mode 1 or mode 2 dependingon the configuration of an eNB.

If another exception condition is not present, only when an eNB performsa configuration, UE may change mode from mode 1 to mode 2 or from mode 2to mode 1.

<ProSe Direct Discovery (D2D Discovery)>

ProSe direct discovery refers to a procedure that is used by aProSe-enabled device to discover another close-ranged ProSe-enableddevice, and this may also be referred to as D2D direct discovery or D2Ddiscovery. At this point, an E-UTRA radio signal may be used through thePC 5 interface. Information that is used for the ProSe direct discoverywill hereinafter be referred to as discovery information.

FIG. 7 shows a PC 5 interface for D2D discovery.

Referring to FIG. 7, the PC 5 interface includes an MAC layer, a PHYlayer, and a ProSe Protocol layer, that is, a higher layer. The higherlayer (the ProSe Protocol) handles the permission of the announcementand monitoring of discovery information. The contents of the discoveryinformation are transparent to an access stratum (AS). The ProSeProtocol transfers only valid discovery information to the AS forannouncement.

The MAC layer receives discovery information from the higher layer (theProSe Protocol). An IP layer is not used to send discovery information.The MAC layer determines a resource used to announce discoveryinformation received from the higher layer. The MAC layer produces anMAC protocol data unit (PDU) for carrying discovery information andsends the MAC PDU to the physical layer. An MAC header is not added.

In order to announce discovery information, there are two types ofresource assignment.

1. Type 1

The type 1 is a method for assigning a resource for announcing discoveryinformation in a UE-not-specific manner. An eNB provides a resource poolconfiguration for discovery information announcement to types of UE. Theconfiguration may be broadcasted through the SIB. The configuration maybe provided through a UE-specific RRC message. Or the configuration maybe broadcasted through other than the RRC message in other layer or maybe provided by UE-specific signaling.

UE autonomously selects a resource from an indicated resource pool andannounces discovery information using the selected resource. The UE mayannounce the discovery information through a randomly selected resourceduring each discovery period.

2. Type 2

The type 2 is a method for assigning a resource for announcing discoveryinformation in a UE-specific manner. UE in the RRC_CONNECTED state mayrequest a resource for discovery signal announcement from an eNB throughan RRC signal. The eNB may announce a resource for discovery signalannouncement through an RRC signal. A resource for discovery signalmonitoring may be assigned within a resource pool configured for typesof UE.

An eNB 1) may announce a type 1 resource pool for discovery signalannouncement to UE in the RRC_IDLE state through the SIB. Types of UEwhose ProSe direct discovery has been permitted use the type 1 resourcepool for discovery information announcement in the RRC_IDLE state.Alternatively, the eNB 2) announces that the eNB supports ProSe directdiscovery through the SIB, but may not provide a resource for discoveryinformation announcement. In this case, UE needs to enter theRRC_CONNECTED state for discovery information announcement.

An eNB may configure that UE has to use a type 1 resource pool fordiscovery information announcement or has to use a type 2 resourcethrough an RRC signal in relation to UE in the RRC_CONNECTED state.

As described above, D2D operations generally have diverse advantages inthe aspect of transmitting and receiving signals between close-rangeddevices. For example, a D2D device mat perform data communication at ahigh transmission rate and a low latency. Additionally, the D2Doperation may disperse traffic that is concentrated to a base station.And, if a device performing D2D operations functions as a relay station,the corresponding device may also carry out a function of expanding thecoverage of the base station. The above-described expansion of the D2Dcommunication includes signal transmission and reception betweenvehicles, and, most particularly, vehicle-related communication isreferred to as vehicle-to-everything (V2X) communication.

Herein, for example, in vehicle-to-X (V2X), the term ‘X’ refers to apedestrian (communication between a vehicle and a device carried by anindividual (e.g.: handheld terminal carried by a pedestrian, cyclist,driver or passenger) (V2P), a vehicle (communication between vehicles)(V2V), an infrastructure/network (communication between a vehicle and aroadside unit (RSU)/network (e.g., RSU is a transportationinfrastructure entity (e.g., an entity transmitting speed notifications)implemented in an eNB or a stationary UE)) (V2I/N), and so on.Additionally, for example, for simplicity in the description of theproposed methods, a (V2P communication related) device that is carriedby a pedestrian (or individual) will be referred to as a “P-UE”, and a(V2P communication related) device that is installed in a vehicle willbe referred to as a “V-UE”. Additionally, for example, in the presentinvention, the term ‘entity’ may be interpreted as a P-UE and/or a V-UEand/or an RSU(/network/infrastructure).

A device (or UE or terminal) providing (or supporting) theabove-described D2D operations may be referred to as a D2D device, and adevice providing (or supporting) the above-described V2X operations maybe referred to as a V2X device. Hereinafter, for simplicity in thedescription, although the exemplary embodiments of the present inventionwill be mainly described in the V2X device point of view, the detailscorresponding to the V2X device may also be applied to the D2D device.

The V2X device may perform message (or channel) transmission within aresource pool, which is defined (or signaled) in advance. Herein, aresource pool may refer to a resource (or resources) being defined inadvance in order to allow the device to perform V2X operations (or beingcapable of performing V2X operations). At this point, for example, aresource pool may be defined in the aspect of time-frequency.

<Method allowing ‘V2X communication’ and ‘other Communication’ toCo-Exist>

The following co-existence methods propose a method allowing ‘V2Xcommunication’ and ‘other communication (e.g., ‘DSRC/IEEE 802.11pservice’, ‘new RAT (NR) eV2X service (based on another numerology)’)’ toefficiently co-exist within the same channel(/band) that is defined(/signaled) in advance.

Herein, for example, in case the following rules(/methods) are applied,‘fairness’ in the ‘channel(/band) usage rate(/occupation rate)’ may alsobe effectively achieved between different communication types.

For example, the term ‘channel(/band/resource)’ may be interpreted tohave the meaning of ‘carrier(/frequency/pool)’.

[Co-existence Method #1] This method allows V2X UE(s) participating inthe ‘V2X communication’ to omit a (2X communication related)channel/signal transmission operation (this may be interpreted as a typeof ‘silencing period’), in a specific (time/frequency) resource that isdefined(/signaled) in advance, and then to perform an ‘(energy)measurement’ operation.

Herein, for example, (configuration) parameters that are related to the(corresponding) ‘silencing period’ (e.g., cycle period, (time/frequency)resource position(/length), hopping pattern, and so on) may bedesignated in the form of a ‘carrier(/pool)-specific(pre)configuration’.

Herein, for example, by performing the corresponding ‘(energy)measurement’ operation, the V2X UE(s) may be capable of determiningwhether or not ‘another communication (e.g., ‘DSRC/IEEE 802.11pservice’, ‘(other numerology based) NR eV2X service’)’.

Herein, for example, if the ‘(energy) measurement’ value is greater thana threshold value that is defined(/signaled) in advance, a rule may bedefined so as to allow the V2X UE(s) (A) to suspend the ‘V2Xcommunication’ within the corresponding channel(/band) (during apre-defined(/signaled) period of time) and/or (B) (to change the‘resource(/channel/band)’ by which the ‘V2X communication’ is performedin accordance with a pre-defined(/signaled) rule(/(priority) level)and/or) to perform the ‘V2X communication’ (during apre-defined(/signaled) period of time) within the pre-defined(/signaled)(changed) other resource(/channel/band).

Herein, for example, if the ‘(energy) measurement’ value is smaller thanthe pre-defined(/signaled) threshold value, V2X UE(s) may be capable ofcontinuously performing the ‘V2X communication’ within the correspondingchannel(/band) (without any suspension (or interruption)).

Herein, for example, settings may be made so that the(pre-defined(/signaled)) (time(/frequency)) resource that is used forthe detection of the ‘other communication’ (and/or the ‘other RAT’)(e.g., the ‘silencing period’) does not apply a V2X resource poolconfiguration related bitmap (having a pre-defined(/signaled) length).

Herein, for example, in case the corresponding rule is applied, it maybe interpreted that the (pre-defined(/signaled)) (time(/frequency))resource that is used for the detection of the ‘other communication’(and/or the ‘other RAT’) is excluded from the V2X resource poolconfiguration.

For example, a rule may also be defined so as to allow the V2X UE(s) tonotify the detection (status) information corresponding to the ‘othercommunication’ to its neighboring ‘V2X UE(s)’ (and/or ‘(serving) basestation(/RSU)’) through the pre-defined(/signaled) signal(/channel).

Herein, for example, when reporting the corresponding information, theposition information (and/or ‘(in case a position-based resource pool(TDM(/FDM)) division operation is configured(/signaled)) information onthe resource pool(/carrier/channel/band) (index) from which the ‘othercommunication’ is detected’) of the V2X UE(s) may also be included inthe reported information.

Herein, for example, a (serving) base station(/RSU) that has receivedsuch information may notify the corresponding information to the V2XUE(s) (existing within the (reported) neighboring (or same)position(/region)) (e.g., ‘P-UE(S)’) (through a pre-defined signal(e.g., through (WAN) DL(/PDSCH)).

Herein, for example, the (serving) base station(/RSU) that has receivedthe information from the (V-UE(s)) may send instructions (orindications) to the V2X UE(s) existing within a position(/region) (beingadjacent or identical to) the position(/region), in which the ‘othercommunication’ has been detected (and/or pool(/carrier/channel/band))(e.g., ‘P-UE(s)’) to perform ‘activation/deactivation’ of the (related)resource pool and/or to suspend the ‘V2X communication’ (and/or the ‘V2Xmessage TX operation’) and/or to perform switching to anotherpre-defined(/signaled) carrier(/channel/band/pool) (in accordance with apre-defined(/signaled) rule/(priority) level).

Herein, as another example, the V2X UE(s) (e.g., ‘P-UE(s)’) havingreceived the corresponding information (from the (serving) basestation(/RSU)) may consider(/compare) its (current) position (and/or thepool(/carrier/channel/band) in which it is (currently) performing theV2X message TX operation) and may then decide(/determine) whether or notto maintain(/suspend) the V2X message TX operation within the currentpool(/carrier/channel/band) and/or to perform switching to anotherpre-defined(/signaled) carrier(/channel/band/pool) (in accordance with apre-defined(/signaled) rule/(priority) level) and to perform the ‘V2Xcommunication’ (and/or the ‘V2X message TX operation’) within the(changed) other resource(/channel/band) (during a pre-defined(/signaled)period of time).

Herein, for example, a rule may be defined so that the operation ofreporting(/signaling) the corresponding information (performed by theV2X UE(s)) can be performed only in a case where the ‘(energy)measurement’ value is greater than the pre-defined(/signaled) thresholdvalue.

Herein, for example, the ‘(serving) base station(/RSU)’ that hasreceived (or that has received a report on) the detection information ofthe ‘other communication’ from the V2X UE(s) may send instructions (A)to change the ‘carrier(/channel(/band))’ through which the ‘V2Xcommunication’ is being performed (in accordance with apre-defined(/signaled) rule/(priority) level) and/or (B) to change thecommunication type to a ‘UU based V2X communication’.

Herein, for example, V2X UE(s) having received the detection informationof the ‘other communication’ from (adjacent) neighboring V2X UE(s) mayalso (similarly) change the ‘channel(/band/carrier)’ through which the‘V2X communication’ is being performed in accordance with apre-defined(/signaled) rule/(priority) level and/or may suspend the ‘V2Xcommunication’ within the corresponding channel(/band/carrier) (during apre-defined(/signaled) period of time) (and/or may perform the ‘V2Xcommunication’ within a pre-defined(/signaled)channel(/band/carrier/resource) (that is changed in accordance with apre-defined(/signaled) rule/(priority) level) (during apre-defined(/signaled) period of time)).

For example, in order to allow the V2X UE(s) (e.g., P-UE(s)) toefficiently receive the (‘other communication’ detection) informationbeing (re-)transmitted(/relayed) by the (serving) base station(/RSU)(and/or (other) V2X UE(s)), the V2X UE(s) may be controlled to perform‘WAKE-UP’ and/or an ‘attempt to receive the corresponding purposechannel(/signal)’ in accordance with a pre-defined(/signaled) cycleperiod(/pattern) (regardless of the ‘RRC_IDLE state’).

Herein, for example, after performing ‘WAKE-UP’) and reception of (only)the ‘(corresponding) purpose channel(/signal) reflecting(/including) the(most) recent information’, which is transmitted at a most proximate(cycle period) time point before the resource that the V2X UE(s) (e.g.,P-UE(s)) have/has selected(/reserved) for the purpose of V2X message TX(or the transmission operation (time point) of the V2X UE(s) (e.g.,P-UE(s))) (or before a (time(/timing)) offset value that ispre-configured(/signaled) in advance from the resource that the V2XUE(s) (e.g., P-UE(s)) have/has selected(/reserved) for the purpose ofV2X message TX (or the transmission operation (time point) of the V2XUE(s))), the V2X UE(s) (e.g., P-UE(s)) may be capable ofdeciding(/determining) whether or not to perform a (final) ‘V2Xcommunication’ (and/or a ‘V2X message TX operation’) in accordance withthe corresponding (recent) information.

For example, if a (‘V2X communication’ related)(pre-configured(/signaled)) ‘LTE signal(/channel)’ is not detectedwithin a pre-defined(/signaled) specific (time/frequency) resource, andif (at the same time) the ‘(energy) measurement’ value is greater than apre-defined(/signaled) threshold value, a rule may be defined so that itcan be determined that an ‘other communication (e.g., ‘DSRC/IEEE 802.11pservice’, ‘(other numerology based) NR eV2X service’)’ is beingperformed within a proximate distance (and/or a same channel(/band)).

For example, the (serving) base station(/RSU) (and/or (other) V2X UE(s))having received the ‘other communication’ detection (status) informationfrom specific V2X UE(s) may notify the corresponding information to(other) neighboring V2X UE(s) (e.g., ‘P-UE(S)’) (and/or the basestation(/RSU)) (within a coverage or establishing a connection) througha pre-defined channel(/signal).

Herein, for example, such information may be transmitted along withadditional information, such as a ‘position(/identifier) information ofspecific V2X UE(s)’ that is defined(/reported) in advance (and/or‘(index) information on a resource pool(/carrier/channel/band) havingthe ‘other communication’ detected therein’ (in case a position basedresource pool (TDM(/FDM)) division operation is configured(/signaled))and/or ‘(energy) measurement information’) and so on.

For example, according to the above-described rule, in case of V2X UE(s)having suspended the ‘V2X communication’ within the currentchannel(/band) (during a pre-defined(/signaled) period of time) (and/orV2X UE(s) having performed the ‘V2X communication’ within anotherresource(/channel/band)), after having the corresponding V2X UE(s)perform the ‘(energy) measurement’ operation once again within aspecific (time/frequency) resource (within the current channel(/band))that is pre-defined(/signaled), in case the ‘other communication’ is notdetected, a rule may be defined so that the ‘V2X communication’ can beperformed once again (within the current channel(/band)).

As an additional information, a rule may be defined so that there-performing of the ‘V2X communication’ within the currentchannel(/band) can be performed only (A) in case the ‘othercommunication’ is not detected (as a result of the ‘(energy)measurement’ operation) and/or (B) in case a pre-defined(/signaled)backoff(/counter) value is smaller than or equal to ‘0’ (or in case arandom (real number) value (‘X’), which is selected(/picked) within arange of ‘0≤X≤1’, is smaller than or equal to a pre-defined(/signaled)likelihood value).

Herein, for example, the backoff value may decrease as much as apre-defined(/signaled) value (e.g., ‘1’) each time the ‘othercommunication’ is not detected (when performing the ‘(energy)measurement’ operation).

For example, the ‘(energy) measurement’ operation for the detection ofthe ‘other communication (e.g., ‘DSRC/IEEE 802.11p service’, ‘(othernumerology based) NR eV2X service’)’ is required to be performedsimultaneously by V2X UE(s) (being positioned at least within apre-defined(/signaled) distance).

Otherwise, for example, the ‘V2X communication’ (being performed withina proximate distance (and/or within the same channel(/band))) may bemisinterpreted as the ‘other communication’, and, accordingly, the ‘V2Xcommunication’ may be excessively suspended.

Therefore, for example, a rule may be defined so that informationrelated to (time/frequency) resources through which the ‘(energy)measurement’ operation is performed (e.g., cycle period, subframeoffset, (hopping) pattern, and so on) can be configured(/signaled) andapplied based on (not a ‘local time’ but) a ‘global positioning system(GPS) time (or a coordinated universal time (UTC))’ (or a ‘time(synchronization) of the (serving) base station(/RSU)’).

Herein, for example, the (time/frequency) resources through which the‘(energy) measurement’ operation is performed may be configured while(differently or independently) considering a ‘V2X message type (e.g., a‘periodic’ or ‘event-triggered’ V2X message) and/or a ‘V2X messagepriority’ and/or a ‘V2X UE density(/speed)’ and/or a ‘V2X messagepriority’ and/or a ‘V2X UE type’, and so on.

For example, the ‘(energy) measurement’ operation may be (directly)performed (not only by the V2X UE(s) but also) by the (serving) basestation(/RSU).

Herein, for example, the (serving) base station(/RSU) having detectedthe ‘other communication (e.g., ‘DSRC/IEEE 802.11p service’, ‘(othernumerology based) NR eV2X service’)’ within a proximate distance (and/orthe same channel(/band)) may also notify(/instruct) whether or not tosuspend the ‘V2X communication’ (performed within the correspondingchannel(/band)) (and/or whether or not ‘V2X communication’ withinanother resource(/channel/band), which is pre-defined(/signaled)(according to a rule(/(priority) level)) to neighboring V2X UE(s)(and/or the base station(/RSU)) (existing within a coverage orestablishing a connection) (through a pre-defined channel(/signal)).

As yet another example, when ‘cross carrier(/pool) scheduling’ isperformed for diverse purposes/reasons (e.g., for congestion control)(e.g., when the SA transmission and the data transmission are performedin different carriers/(pools), or when a (rear-end) part of thedata(/SA) repetition transmission is performed in a differentcarrier/(pool)), according to a pre-defined(/signaled)rule(/information), a different PHY format may be used in each of thedifferent carriers/(pools).

Herein, for example, in which PHY format (e.g., ‘RS structure’) the V2XUE will be performing the (control/data information) transmission withina specific carrier may be notified (to other V2X UE(s)) through a (new)field within a pre-defined(/signaled) channel (e.g., PSCCH).

Herein, for example, a PHY format of a channel (e.g., PSCCH) being usedfor the ‘scheduling/control information (and/or the used PHY formatinformation)’ transmission may be equally (or commonly) defined betweendifferent carriers(/pools).

As yet another example, the V2X UE(s) may be enabled to perform(transmission) resource (re-)selecting as described below.Hereinafter, 1. Details on an example of a (transmission) resource(re-)selecting operation will be described through Table 1, and 2.Details of an example of a transmission resource(re-)reserving(/selecting) operation of V2X TX UE(s) will be describedthrough Table 2.

TABLE 1 1. Details on an example of a (transmission) resource(re-)selecting operation A V2X device may select a transmission resourceby using the following method. It is assumed that the device is beingoperated in a mode allowing the device to select a resource on its own.While being operated in this mode, when a resourceselection/re-selection for a V2X message transmission is triggered, thedevice (or UE) performs sensing and selects/re-selects a resource basedon the sensing result. The UE may transmit a scheduling assignment (SA)indicating the selected/re-selected resource. For example, a resourceselection/re-selection may be triggered to the device from subframe(also referred to as TTI, and hereinafter referred to as the same) #n.Accordingly, the device may perform sensing between subframe #n − a andsubframe #n − b (wherein a > b > 0, and wherein a and b are integers)and may select/re-select the source for the V2X message transmissionbased on the sensed result. The integers a and b may correspond tovalues being commonly configured to the V2X UEs or may correspond tovalues being independently configured to each V2X UE. Alternatively, incase the above-described values a and b correspond to values that arecommon to all V2X UEs, for example, the values a and b may establish arelationship such as ‘a = 1000 + b’. More specifically, if triggeringoccurs so that the UE selects its own resource for transmitting the V2Xmessage, the UE may perform a sensing operation during a period of 1second (1000 ms = 1000 subframes = 1000 TTIs). The UE may consider thetransmission of all decoded SAs during a second stating from subframe #n− a to subframe #n − b. The decoded AS may be associated with the datatransmission during a section starting from subframe #n − a to subframe#n − b, and it may be considered that the decoded SAs has beentransmitted before the subframe #n − a. The UE(s) that has/have failedto perform the sensing operation in subframe #m (e.g., for reasons of asignal having to be transmitted from the subframe #m, and so on) mayexclude subframes #(m + 100*k) from the resource selecting/re-selecting. Meanwhile, in subframes that are used by the UE fortransmitting its own signals may be skipped without performing thesensing operation. After performing the sensing operation, the UEselects time/frequency resources for a PSSCH, i.e., a sidelink datachannel. The UE may transmit a scheduling assignment (SA) from subframe#n + c. Herein, c corresponds to an integer greater than or equal to 0,and, herein, c may correspond to a fixed value or a variable value. Thescheduling assignment transmission (i.e., PSCCH transmission) may not berequired to be performed by the UE in subframes wherein the c value issmaller than c_(min). Herein, the c_(min) value may correspond to afixed value or may correspond to a value that is configured by thenetwork. The scheduling assignment (SA) being transmitted from subframe#n + c may indicate associated data being transmitted from subframe #n +d. Herein, d may correspond to an integer greater than or equal to c (d≥ c). And, both the c and d values may be smaller than or equal to 100.d may correspond to a value that is smaller than or equal to d_(max).Herein, the value d_(max) may be dependently determined according topriority levels, such as UE/data/service types, and so on. The UE maynotify whether or not the frequency resource for the signal beingtransmitted from subframe #n + d will be reused for a potentialtransmission of another transmission block from subframe #n + e. Herein,e is an integer establishes a relationship of d < e. The UE mayexplicitly or implicitly notify whether or not the correspondingfrequency resource will be reused. The e value may correspond to onevalue or may correspond to a plurality of values. Also, additionally,the UE may notify that the frequency resource for the signal beingtransmitted from subframe #n + d will not be reused starting from aftersubframe #n + e. A receiving UE receiving a V2X signal decodes ascheduling assignment (SA), which is transmitted by a transmitting UEtransmitting a V2X signal. At this point, it may be assumed that thesame frequency resource is reserved in subframe #n + d + P*j (wherein j= i, 2*i, . . . , J*i) by the scheduling assignment. Herein, P may beequal to 100. The J value may be explicitly signaled by the schedulingassignment, or the J value may correspond to a fixed value (e.g., 1).The i value may be explicitly signaled by the scheduling assignment, orthe i value may correspond to a pre-configured value or a fixed value.Alternatively, the i value may correspond to an integer ranging between0 and 10. Meanwhile, if any one of the following conditions issatisfied, the re- selecting of the V2X resource may be triggered. 1. Incase the counter satisfies the expiration condition. The value of thecounter decreases at each transmission of the transmission block, and,when the re-selecting is triggered for all of the semi-persistentlyselected resources, the counter value may be reset. The reset values maybe randomly selected within a specific range, e.g., within a range of 5to 15 at equal possibilities. 2. In case the transmission block does notmatch the current resource assignment even if a tolerated maximummodulation and coding scheme (MCS) is used. 3. In case instructions aremade from a higher-level layer, and so on. Meanwhile, in case all of thePSCCH/PSSCH transmission have the same priority level, theselecting/re-selecting of the PSSCH resource may be selected afterundergoing the following process. Firstly, after considering that allresources are available to be selected, specific resources are excludedbased on the scheduling assignment decoding and additional conditions.At this point, the UE may select any one of the two options listedbelow. The first option corresponds to excluding resources beingindicated or reserved by the decoded scheduling assignment and resourceshaving a DM-RS power, which is received from data resources beingassociated with the scheduling assignment, that is equal to or greaterthan a threshold value. The second option correspond to excludingresources being indicated or reserved by the decoded schedulingassignment and resources having an energy level, which is measured fromdata resources being associated with the scheduling assignment, that isequal to or greater than a threshold value. The UE may select V2Xtransmission resources from the resources that are not excluded. Forexample, after measuring the remaining PSSCH resources based on thetotal received energy and ranking the measured resources, the UE mayselect a subset. The UE may compare the energy from the currentlyselected resources with the energy of the subset. Then, when the energyfrom the currently selected resources is greater than the thresholdvalue as compared to the energy of the subset, any one of the energy ofthe subset may be selected. The UE may randomly select one resource fromthe subset. Alternatively, after measuring the remaining PSSCH resourcesbased on the total received energy and ranking the measured resources,the UE may select a subset. The UE may randomly select one resource fromthe subset. Alternatively, after measuring the remaining PSSCH resourcesbased on the total received energy and ranking the measured resources,the UE may select a subset. The UE may select a resource that canminimize fragmentation of the frequency resource from the subset.Alternatively, the UE may measure the received energy (or power) of thePSSCH that is indicated by the decoded scheduling assignment. And, then,after adding the measured energy to obtain the total received energy,the UE may sort the subframes in accordance with the total receivedenergy. The UE may randomly select a transmission subframe from a set ofsubframes being available for usage. Thereafter, the UE may randomlyselect a frequency from the transmission subframe. During theabove-described process, the UE first excluded a specific resource basedon the scheduling assignment and the additional conditions and, then,selected the V2X transmission resource. At this point, in case thescheduling assignment and the data associated with the schedulingassignment are transmitted from the same subframe, a method of excludingthe resource based on the DM-RS receiving power of the PSSCH may besupported. More specifically, the resources being indicated or reservedby the decoded scheduling assignment and resources having a PSSCHreference signal received power (RSRP), which is received from dataresources being associated with the scheduling assignment, that is equalto or greater than a threshold value are excluded. More specifically,the PSSCH RSRP may be defined as a linear average of the powerdistribution of resource elements (REs) carrying DM-RSs that areassociated with the PSSCH within physical resource blocks (PRBs)indicated by the PSCCH. The PSSCH RSRP may be measured from a referencepoint, which corresponds to an antenna connection part of the UE. Thescheduling assignment may include a 3-bit PPPP field. The thresholdvalue may be given in the format of a function corresponding to prioritylevel information. For example, the threshold value may be dependent tothe priority level information of the transmission blocks and thepriority level information of the decoded scheduling assignment. Thethreshold value may be given in units of [2 dBm] within a range of [−128dBm] to [0 dBm], A total of 64 threshold values may be predetermined. Itmay be assumed that the UE decodes the scheduling assignment fromsubframe #m + c, which exists within the sensing section, and that thesame frequency resource is being reserved by the scheduling assignmentin subframe #m + d + P*i. As described above, P may correspond to afixed value that is equal to 100. And, i may be selected from a range of[0, 1, . . . , 10], Herein, i may be carrier-specifically configured bythe network or may be pre-configured in advance. i = 0 indicates thatthe frequency resource is not intended to be reserved. Herein, i may beconfigured by a 10-bit bitmap and may be configured as a 4-bit fieldwithin the scheduling assignment. In the cycle period P*I, a candidatesemi-persistent resource X collides with resource Y, which is reservedby the scheduling assignment of another UE. And, in case the conditionof exclusion is satisfied, the UE may exclude the candidatesemi-persistent resource X. Herein, I may represent an i value that issignaled by the scheduling assignment. After excluding resources afterperforming scheduling assignment decoding, a sensing process, and so on,in case the remaining resources are less than 20% of the total resourceswithin the selecting window, the UE may increase the threshold value(e.g., 3 dB). Thereafter, the UE may repeat the process of excludingresources. And, this process may be performed until the remainingresources become greater than 20% of the total resources within theselecting window. The total resources within the selecting window referto resources that the UE is required to consider as possible candidateresources. Meanwhile, during the process of selecting a V2X transmissionresource after excluding a specific resource, when the counter reaches avalue of 0, the UE may maintain the current resource at a possibility pand may reset the counter. More specifically, the resource may bere-selected at a possibility of 1 − p. After measuring the remainingPSSCH resources after excluding the specific resources and, then,ranking the measured resources based on the total received energy, theUE select a subset. The subset may correspond to a set of candidateresources having the lowest received energy. Herein, the size of thesubset may correspond to 20% of the total resources within the selectingwindow. The UE may randomly select one resource from the subset. Whenonly one transmission block is transmitted from one subframe, the UE mayselect M number of continuous sub-channels, and an average value of theenergy measured from each sub-channel may correspond to the energy valuemeasured from each resource.

TABLE 2 2. Details of an example of a transmission resource(re-)reserving(/selecting) operation of V2X TX UE(s) 2.1. UE procedurefor determining subframes and resource blocks for transmitting PSSCH andreserving resources for sidelink transmission mode 4 The number ofsubframes in one set of time and frequency resources for a transmissionopportunity of the PSSCH is given as C_(resel). At this point, in caseC_(resel) is selected, the corresponding value is given as[10*SL_RESOURCE_RESELECTION_COUNTER], and, otherwise, the value ofC_(resel) may be Set to 1. In case a set of sub-channels in subframet_(m) ^(SL) is determined just as the time and frequency resources thatare related to the PSSCH transmission corresponding to a configuredsidelink grant, the same sets of sub-channels within subframes t_(m)^(SL) _(+ P) _(rsvp*) _(j) may be determined for PSSCH transmissionscorresponding to the sidelink grant. Herein, j = 1, 2, . . . , andresource reservation intervals for C_(resel) − 1 and P_(rsvp) may bedetermined by higher-level layers. 2.2. UE procedure for transmittingthe PSCCH In relation to the Sidelink Transmission Mode 4, the UE mayconfigure the contents of the SCI Format 1 as described below. In casethe SL_RESOURCE_RESELECTION_COUNTER is greater than 1, the UE configuresa resource reservation field as a resource reservation section, which isdetermined by higher-level layers that are separated by P_(step).Herein, P_(rsvp) = 100. And, otherwise, the UE sets the resourcereservation field to 0. 2.3. UE procedure for determining the subset ofresources to be excluded in PSSCH resource selection in sidelinktransmission mode 4 In case a request is made by the higher-level layersin subframe n, the UE determines a set of resources being excluded fromthe PSSCH transmission according to the following steps listed below.The higher-level layer may determine a parameter L_(subCH) correspondingto a number of sub-channels being used in the subframe for the PSSCHtransmission, a parameter P_(rsvp) _(—) _(TX) corresponding to resourcereservation intervals that are determined by the higher- level layer,and a parameter prio_(TX) corresponding to priority levels transmittedin SCI Format 1, which is associated by the UE. STEP 1) A candidatesingle subframe resource R_(x, y) being related to the PSSCHtransmission may be determined just as a set of adjacent sub-channelsL_(subCH) along with sub-channel x + j in subframe t_(y) ^(SL). Herein,an equation of j = 0, . . . , L_(subCH) − 1 may be established. STEP 2)The UEmonitors subframes n − 1001, n − 1000, n − 999, . . . , n − 2excluding the transmission opportunity of the UE. STEP 3) ParameterTh_(a, b) may be set to be equal to a value that is starts by an i-thSL-ThresPSSCH-RSRP field in an SL-ThresPSSCH-RSRP-List-r14. At thispoint, i = a * 8 + b + 1. STEP 4) Set S_(A) may be initialized to acombination of all candidate single subframe resources. And, Set S_(B)may be initialized to an empty set. STEP 5) In case the followingcondition is satisfied, the UE excludes the candidate single subframeresource R_(x, y) from Set S_(A). The UE may receive SCI Format 1 insubframe t_(m) ^(SL). And, in the received SCI Format 1, a ‘resourcereservation’ field and a ‘priority’ field may respectively indicatevalues of P_(rsvp) _(—) _(RX) and prio_(RX). The PSSCH-RSRP measurementaccording to the received SCI Format 1 may be greater than Th_(prio)_(TX) _(, prio) _(RX) . The same SCI Format 1, which is presumed to bereceived in subframe t_(m) ^(SL) _(+ P) _(step) _(· P) _(rsvp) _(—)_(RX) , may be determined in accordance with the resource blocks and aset of subframes overlapping with 

 , which is related to j = 0, 1, . . . C_(resel) − 1. STEP 6) In casethe number of candidate single subframe resources remaining from SetS_(A) is less than 0.2 · M_(total), STEP 4 may be repeated along withTh_(a, b), which is increased by 3 dB. STEP 7) In relation to thecandidate single subframe resource R_(x, y) remaining in Set S_(A), ametric E_(x, y) may be defined as a linear average of S-RSSI, which ismeasured in sub-channel x + k in relation to k = 0, . . . L_(subCH) − 1in the subframes that are monitored in STEP 2. STEP 8) The UE mayrelocate the candidate single subframe resource R_(x, y) along with aminimum metric E_(x, y) from set S_(A) to set S_(B). This step may berepeated. STEP 9) Set S_(C) may be defined as a set of all of thecandidate single subframe resources that are not included in set S_(B).

For example, the following co-existence methods listed below proposemethods for effectively performing a V2X communication related ‘sensingoperation’ and/or ‘resource (re-) selecting operation’, when the V2XUE(s) detect(s) the other communication (e.g., ‘DSRC/IEEE 802.11pservice’, ‘(other numerology based) NR eV2X service’) within a specificchannel(/band/carrier) according to the (above-described) rule andperform(s) a ‘channel(/band/carrier) switching(/changing) operation’.

Herein, for example, the wording of the term “sensing” may beinterpreted as an energy measurement operation for apre-defined(/signaled) reference signal (RS) and/or channel (e.g., DM-RSRSRP and/or S-RSSI of a PSSCH (being interconnected to the decodedPSCCH)), or may be interpreted as a decoding operation for apre-defined(/signaled) channel (e.g., physical sidelink control channel(PSCCH)).

Herein, for example, since a ‘congestion level’ of a specificchannel(/band/carrier) wherein the V2X communication is performedbecomes higher (than a pre-configured(/signaled) threshold value), theabove-described (partial) co-existence methods may be extendedly appliedto a case where the V2X UE(s) perform a ‘channel(/band/carrier)switching(/changing) operation’ in accordance with a pre-defined rule(or a received signaling(/indicator) (received from the (serving) basestation(/RSU))).

[Co-Existence Method #2]

When the V2X UE(s) perform the ‘channel(/band/carrier)switching(/changing) operation’, this method allows the resources thatare to be used in the V2X communication to be randomly (re-)selected(from a ‘V2X resource pool’ within a switched(/changed)channel(/band/carrier)).

Herein, for example, the ‘channel(/band/carrier) switching(/changing)operation’ may also be interpreted as a type of condition according towhich the ‘(transmission) resource (re-) selection’ istriggered(/performed).

Herein, for example, the resources that are randomly (re-)selectedaccording to the above-described rule (may only be used for apre-configured(/signaled) number (e.g., ‘1’) of ‘transmission block(TB))’ transmissions after performing the ‘channel(/band/carrier)switching(/changing) operation’ and) may be prevented from beingprocessed with ‘reservation’(/‘semi-persistent scheduling (SPS)’) (for a(plurality of) ‘TB’ transmission(s) that is/are to be performed lateron), or may be prevented from being used(/reserved) as (frequency)resources being used in the (plurality of) ‘TB’ transmission(s) thatis/are to be performed later on.

Herein, as another example, when performing the ‘channel(/band/carrier)switching(/changing) operation’, the randomly (re-)selected resourcesmay be (exceptionally) processed with ‘reservation’(/‘SPS’) (for (aplurality of (or a pre-configured(/signaled) number of) ‘TB’transmissions)), or may be used(/reserved) as (frequency) resourcesbeing used for (a plurality of (or a pre-configured(/signaled) numberof) ‘TB’ transmissions.

As yet another example, after (first) performing the ‘sensing’ operationduring a pre-configured(/signaled) time section within theswitched(/changed) channel(/band/carrier), this method allows the V2XUE(s) to (re-)select (optimal) resources that are to be used in the V2Xcommunication based on the processed result.

Herein, for example, the corresponding ‘sensing time section’ value(and/or the “PSSCH-RSRP measurement” threshold value in STEP 5 ofSection 2.3. in Table 2 (and/or the “0.2*M_(total)” relatedcoefficient(/ratio) value in STEP 6(/8) of Section 2.3. in Table 2 (forexample, this may be interpreted as a ratio value drawing(/determining)a minimum number of (candidate) resource that should remain (in Set SA)(among the total (candidate) resources) after performing STEP 5 ofSection 2.3. in Table 2 and/or a ratio value drawing(/determining) a(minimum) number of (candidate) resources that should remain in Set SBafter performing STEP 8 of Section 2.3. in Table 2) and/or a “PSSCH-RSRPmeasurement” increase value that is to be applied in case the minimumnumber of (candidate) resources that should remain in Set SA (among thetotal (candidate) resources) after performing STEP 5 of Section 2.3. inTable 2 is not satisfied (e.g., “3DB”) and/or a cycle period value beingused in the sensing operation (e.g., STEP 5 of Section 2.3. in Table 2)(and/or a cycle period value being used in the energy measurementoperation (e.g., STEP 8 of Section 2.3. in Table 2))) may beconfigured(/signaled) differently from the value (e.g., ‘1000MS’) thatis applied(/used) when the ‘channel(/band/carrier) switching(/changing)operation’ is not performed (e.g., a relatively smaller (or greater)value) (or may be identically configured(/signaled)).

Herein, as another example, when performing the transmission resource(re-) reservation(/selection), a limited number of subframes(corresponding to a resource reservation (interval) cycle period) beingassumed(/used) (and/or the Cresel value is Section 2.1. of Table 2(e.g., “[10*SL_resource_reselection_counter]”)) and/or an I_VALUE(range) value that can be selected(/tolerated) from a V2X messagepriority level and/or a V2X resource pool (and/or a (V2X) carrier)and/or a P_STEP value and/or a transmission power related (open-loop)parameter(/value) (e.g., “Po”, “ALPHA”, and so on) may be differentlyconfigured(/signaled) from the values being applied(/used) when the‘channel(/band/carrier) switching(/changing) operation’ is not performed(or may be equally configured(/signaled)).

[Co-Existence Method #3]

When the V2X UE(s) perform(s) the ‘channel(/band/carrier)switching(/changing) operation’, the resources that are to be used inthe V2X communication may be (re-)selected (from the ‘V2X resource pool’within the switched(/changed) channel(/band/carrier)) according to (partof) the rule described below.

Example #3-1

Although the ‘channel(/band/carrier) switching(/changing) operation’ isperformed, if a packet(/message) (that is to be transmitted to or thatis generated) in a ‘(low layer) buffer’ (and/or a ‘PDCP layer’) does notexist (or if a packet(/message) is not generated), the V2X UE(s) mayalso (partially) perform the ‘sensing’ operation (for the ‘V2X resourcepool’ within the switched(/changed) channel(/band/carrier)).

Herein, for example, the V2X UE(s) may perform the ‘(partial) sensing’operation until a packet(/message) (that is to be transmitted to or thatis generated) in its/their ‘(low layer) buffer’ (and/or a ‘PDCP layer’)exists(/is achieved) (or until a packet(/message) is generated) (or onlyduring a pre-configured(/signaled) time section).

Herein, for example, in case the above-described rule is applied, theV2X UE(s) may finally (re-)select a most adequate (transmission)resource (from the ‘V2X resource pool’ within the switched(/changed)channel(/band/carrier)) based on the result of the ‘(partial) sensing’operation.

Herein, for example, the V2X UE(s) may (limitedly) (re-)select its/their(transmission) resource only in the resource (region) wherein the‘(partial) sensing’ operation is performed.

Herein, for example, (frequency) resources (being related to a(plurality of) ‘TB’ transmissions) may be defined to be processed with‘reservation’(/‘SPS’) only in a case where the ‘(partial) sensing’operation is performed.

As another example, although the ‘channel(/band/carrier)switching(/changing) operation’ is performed, in case a long ‘latency’(longer than a pre-configured(/signaled) threshold value) still remains,the V2X UE(s) may (partially) perform the ‘sensing’ operation (for the‘V2X resource pool’ within the switched(/changed)channel(/band/carrier)).

Example #3-2

In accordance to whether or not a pre-configured(/signaled) condition issatisfied (in the above-described (Example #3-1)), the V2X UE(s) mayperform(/select) any one of (A) resource (re-)selection based on the‘(partial) sensing’ operation and (B) ‘random’-based resource(re-)selection.

Herein, for example, in case the following condition is (partially)satisfied, the V2X UE(s) may perform the ‘random’-based resource(re-)selection (or the resource (re-)selection based on the ‘(partial)sensing’ operation), and, otherwise, the V2X UE(s) may perform theresource (re-)selection based on the ‘(partial) sensing’ operation (orthe ‘random’-based resource (re-)selection).

Example #3-2-1

When the ‘channel(/band/carrier) switching(/changing) operation’ isperformed, a case where a (newly) generated packet(/message) (or apacket(/message) that is to be transmitted) exists (in a ‘(low layer)buffer’ (and/or a ‘PDCP layer’)).

Example #3-2-2

When the ‘channel(/band/carrier) switching(/changing) operation’ isperformed, a case where a short ‘latency’ (shorter than apre-configured(/signaled) threshold value) still remains.

Example #3-2-3

When the ‘channel(/band/carrier) switching(/changing) operation’ isperformed, a case where a ‘(reselection) counter’ value, which isrelated to a resource that is (re-)selected from the ‘V2X resource pool’within the initial channel(/band/carrier), is smaller than or equal to(or greater than) a pre-configured(/signaled) (e.g., ‘0’) (and/or a casewhere V2X UE(s) perform(s) (or cannot perform) ‘TB’ transmission byre-using the (re-)selected (frequency) resource as many times as(its/their) pre-configured(/signaled) number(/cycle period) ofre-usage).

Example #3-3

When the ‘channel(/band/carrier) switching(/changing) operation’ isperformed, in case a ‘(reselection) counter’ value, which is related toa resource that is (re-) selected from the ‘V2X resource pool’ withinthe initial channel(/band/carrier), is greater than or equal to (orsmaller than) a pre-configured(/signaled) (e.g., ‘0’) (and/or a casewhere V2X UE(s) perform(s) (or cannot perform) ‘TB’ transmission byre-using the (re-)selected (frequency) resource as many times as(its/their) pre-configured(/signaled) number(/cycle period) ofre-usage), and/or in case a (newly) generated packet(/message) (or apacket(/message) that is to be transmitted) exists (or does not exist)(in a ‘(low layer) buffer’ (and/or a ‘PDCP layer’)), and/or in case ashort (or long) ‘latency’ (shorter (or longer) than apre-configured(/signaled) threshold value) still remains, the positionsof the V2X communication related (transmission) resources within theswitched(/changed) channel(/band/carrier) may (at least)succeed(/maintain) the same positions as the initialchannel(/band/carrier).

Herein, for example, in case the above-described rule is applied, it maybe interpreted that (part of) the parameters related to the(transmission) resource (re-)selection within the initialchannel(/band/carrier) (e.g., ‘(reselection) counter’, number oftimes(/cycle period) performing the ‘TB’ transmission by re-using the(re-)selected (frequency) resource, and so on) are succeeded to theswitched(/changed) channel(/band/carrier).

Herein, for example, the rule may be limitedly applied only to a casewhere the V2X communication related ‘resource poolconfiguration(/bandwidth)’ within the initial channel(/band/carrier) isidentical to that of the switched(/changed) channel(/band/carrier).

For example, when the ‘channel(/band/carrier) switching(/changing)operation’ is performed, and in case the position of the V2Xcommunication related (transmission) resource within theswitched(/changed) channel(/band/carrier) is configured by (re-)usingthe sensing result corresponding to the initial channel(/band/carrier),the V2X UE(s) may only consider the overlapping (V2X communicationrelated) resource (pool) region between the initialchannel(/band/carrier) and the switched(/changed) channel(/band/carrier)(within a logical resource region), so as to select(/reserve) the (most)adequate resource among the overlapping region (based on the sensingresult corresponding to the initial channel(/band/carrier)).

Herein, for example, when the ‘channel(/band/carrier)switching(/changing) operation’ is performed, and in case the positionof the V2X communication related (transmission) resource within theswitched(/changed) channel(/band/carrier) is configured by (re-)usingthe sensing result corresponding to the initial channel(/band/carrier),if the corresponding configured (transmission) resource position (thatis configured by (re-)using the sensing result corresponding to theinitial channel(/band/carrier)) is (already) occupied by another V2X UE(or other V2X UEs) within the switched(/changed) channel(/band/carrier)(for example, this may be interpreted as a case where the V2X UE(s))has/have performed (in advance) the sensing operation corresponding tothe switched(/changed) channel(/band/carrier), the V2X UE(s) may (A)reselect (and/or randomly select) only the corresponding collided(transmission) resources and/or (B) use only the remaining(transmission) resources that are not collided(/overlapped) for thepurpose of (V2X message) transmission.

For example, while the V2X UE(s) (having the receiving(/sensing)capability related to a plurality of channels(/bands/carriers))perform(s) sensing(/reception) operations corresponding to the(corresponding) plurality of channels(/bands/carriers) (and/or othercommunication (e.g., ‘DSRC/IEEE 802.11p service’, ‘(other numerologybased) NR eV2X service’) detection operation), when anothercommunication is detected within the channel(/band/carrier) throughwhich the V2X UE(s) is/are currently performing the (V2X message)transmission operation, (with the exception for the correspondingchannel(/band/carrier),) the V2X UE(s) may select one of the(corresponding) plurality of channels(/bands/carriers) through which thesensing(/reception) operation (and/or the other communication detectionoperation) was/were performed and may, then, perform the‘channel(/band/carrier) switching(/changing) operation’.

Herein, for example, among the (corresponding) plurality ofchannels(/bands/carriers), (A) a channel(/band/carrier) having a(relatively) low congestion level (and/or a sensed energy measurementvalue) and/or (B) a channel(/band/carrier) having (relatively) lessresources being occupied by the other V2X UE(s) and/or (C) achannel(/band/carrier) having no other communication detected thereinand/or (E) a channel(/band/carrier) of a (relatively) low (or high)index may first be selected (and/or a channel(/band/carrier) of a(higher (or lower) (priority)) level according to apre-configured/(signaled) (priority) level) may first be selected) ormay be randomly selected.

For example, in order to perform the (V2X message) transmission, whilethe V2X UE(s) uses a (pre-configured(/signaled)) specificcarrier(/channel(/band)), when it is determined that another(pre-configured(/signaled)) carrier(/channel(/band)) has a lower‘congestion level’ (and/or ‘load level’), if the V2X UE(s) switches tothe (corresponding) other carrier(/channel(/band)) immediately (or rightaway), this may cause the system to become instable.

Herein, for example, in order to resolve the corresponding problem, (A)a timer for maintaining the (V2X message) transmission within theinitial carrier(/channel(/band)) may be configured(/signaled) (beforethe (‘congestion level’ (and/or ‘load level’) based)carrier(/channel(/band)) switching is applied) and/or (B) a switchingoperation to another carrier(/channel(/band)) (having a relatively low‘congestion level’ (and/or ‘load level’)) may be (limitedly) performedonly when a ‘congestion level difference’ (and/or ‘load leveldifference’) between the initial carrier(/channel(/band)) and anothercarrier(/channel(/band)) exceeds a pre-configured(/signaled) thresholdvalue (for example, this may be interpreted as a type of (‘congestionlevel’ (and/or ‘load level’) based) ‘hysteresis’).

For example, it will be assumed that a resource (RES_L) beingconfigured(/signaled) to have a ‘RAT’ of a (relatively) low prioritylevel for the V2X UE(s) and that a resource (RES_H) beingconfigured(/signaled) to have a ‘RAT’ of a (relatively) high prioritylevel exist (ref Table 3).

Herein, for example, while the V2X UE(s) perform(s) the V2Xcommunication, if a (measured) (‘RESH’ related) ‘congestion level’ valuebecomes greater than a pre-configured(/signaled) threshold value(CL_RSC_H) (for example, the ‘CL_RSC_H’ may be interpreted as athreshold value being interconnected with the ‘RES_H’), and if the V2XUE(s) consider(s) switching(/offloading) to ‘RES_L’ accordingly,(actual) switching (from ‘RES_H’ to ‘RES_H’) may be allowed only whenthe ‘RES_L’ related (measured) ‘congestion level’ value is smaller thanthe pre-configured(/signaled) threshold value (CL_RSC_L) (for example,‘CL_RSC_L’ may be considered as a threshold value being interconnectedwith the ‘RESL’).

Herein, for example, the ‘CL_RSC_H’ and the ‘CL_RSC_L’ may beconfigured(/signaled) as different values (e.g., ‘CL_RSC_H>CL_RSC_L’).

For example, the V2X UE(s) may perform a ‘congestion level’ (and/or‘load level’) measurement operation (and/or ‘other communication’ (e.g.,‘DSRC/IEEE 802.11p service’, ‘(other numerology based) NR eV2X service’)(and/or ‘other RAT’) detection operation) even in a(pre-configured(/signaled)) (external) resource region other than a V2Xresource pool (that is designated to have a ‘carrier(/cell)-specificnetwork (pre)configuration’ format.

Herein, for example, if the corresponding ‘congestion level’ (and/or‘load level’) measurement result (corresponding to the (external)resource region) is high, it may be determined that an ‘othercommunication’ (and/or ‘other RAT’) exist(s).

Herein, for example, the corresponding ‘congestion level’ (and/or ‘loadlevel’) measurement (corresponding to the (external) resource region)(and/or the ‘other communication’ (and/or ‘other RAT’) detection) may beperformed in a (separate) pre-configured(/signaled) sub-channel (withinthe (external) resource region) and/or may be performed through theentire band (within the (external) resource region).

Herein, for example, the (‘congestion level’ (and/or ‘load level’)measurement related) (S-RSSI) measurement operation may be performedwithin the V2X resource(s) without any V2X resource pool distinction.

Herein, for example, the corresponding (‘congestion level’ (and/or ‘loadlevel’) measurement related) (S-RSSI) measurement operation may beperformed in a ‘(V2X) pool-specific’ (or ‘(V2X) pool-common) format, andregions excluding the (V2X) pool may be measured separately.

Herein, for example, in (part of) the above-described rule, themeasurement operation (within the V2X resource(s)) may be performed onlyin the (V2X) TX pool (and/or (V2X) RX pool) (within the correspondingcarrier).

For example, in case the (‘V2X communication’ (and/or ‘V2X message TXoperation’) related) carrier(/channel/band/pool) is to be switched bythe V2X TX UE(s) (according to the pre-configured(/signaled)rule(/(priority) level), the V2X TX UE(s) may signal(/broadcast) (inadvance) to the (neighboring) V2X RX UE(s) through a pre-defined channel(e.g., ‘PSCCH(/PSSCH)’ and/or ‘PSBCH)’) information indicating to whichcarrier(/channel/band/pool) the V2X TX UE(s) intend(s) to performswitching.

Herein, for example, the (specific) carrier(/channel/band/pool) throughwhich the channel of the corresponding purpose is to be transmitted maybe pre-configured(/signaled) (in a ‘UE-common’ format).

For example, Table 3 shows a method enabling the ‘V2X communication’ andthe ‘other communication’ (e.g., ‘DSRC/IEEE 802.11p service’, ‘(othernumerology based) NR eV2X service’) to efficiently co-exist.

TABLE 3 3. Example of a method enabling the ‘V2X communication’ and the‘other communication’ to efficiently co-exist Proposal 1: An LTE SL V2Vdesign for the co-existence with a Dedicated Short-Range Communications(DSRC) should consider the co-existence with the NR V2X. Morespecifically, an LTE SL V2V design for the co-existence with the NR V2Xshould be considered. 3.1. Solutions that can be identified in an SIphase Proposal 2: A RAN1 specification resource may not be required inthe “geographical location and database” and “time sharing between GNSStiming- based systems” options. 3.2. Detection of another RAT Proposal3: When the LTE UE senses a high energy level from a resource performingno LTE transmission, the LTE UE may detect the presence of another RAT.A “resource having no LTE transmission” may correspond to a resourcethat is configured just as the implicit resources or a resource havingno LTE signals discovered therein. Proposal 4: Even in case a loadcorresponding to an LTE SL V2V is high, a solution may be required inorder to ensure a transmission opportunity of IEEE 802.11p. In order toensure detectability, the reference line may correspond to transmittinga detection signal by the UE each time the PSCCH/PSSCH is transmittedfrom the subframe. One of the methods corresponds to using a firstand/or last symbol(s) (including a possibility of using part of suchsymbols) within a frequency resource of a corresponding PSCCH/PSSCH.However, this design should ensure the operations performed in thissymbol. Herein, in the first symbol, an automatic gain control (AGC)operation may be performed, and, in the last symbol, a TX/RX switchingoperation and an absorbing operation of an uplink (UL) TX timing advancemay be performed. Hereinafter, two different options corresponding tothe detection signal of the LTE SL V2V will be described in detail. FIG.8 is an example of an LTE SL V2V detection signal using time repetitionof a short sequence. According to FIG. 8, in the first option, a shortsequence may be repeated within the time domain within the first and/orlast symbol(s). The operation of the intended detection devicecorresponds to using a so-called “delay correlation” between a nextreceiving signal following the time domain receiving signal that isdelayed for as much as a detection sequence length and a correlatedreceiving signal. In this operation, although the UE does not detect thesequence itself, the UE is capable of identifying a specific repetitionpattern of a signal in the time domain. Therefore, the UE is notrequired to know the accurate sequence that is used by the transmitter,and this may correspond to an advantage of a detector using another RAT.FIG. 9 is an example of an LTE SL V2V detection signal using sequencematching in the frequency domain. According to FIG. 9, in the secondoption, the detection device may match each sequence of each frequencyresource. Since the transmission bandwidth of the PSSCH may not be knownto the detection device, in order to allow all UEs to use the samesequence while adequately maintaining a single carrier, a resource block(RB) size of a detection signal is fixed to have the same size as, forexample, one sub-channel. In order to allow the first symbol to supportthe AGC and to maintain the same coverage, a Power Spectral Density(PSD) is required to be boosted during the transmission of a detectionsignal, which uses part of the PSSCH transmission bandwidth. Proposal 5:When a pre-decided signal is used for an inter-RAT detection, a new LTESL signal is required to be transmitted from a first and/or finalsymbol(s) of all subframes from which the UE transmits the PSCCH/PSSCH.Herein, the AGC operation should be ensured in the first symbol, and theTX/RX switching operation and the absorbing operation of a UL TX timingadvance should be ensured in the last symbol. 3.3. Usage of resourcesthat are potentially shared with another RAT A detect-and-vacateoperation assumes a prioritized access to a resource. In other words,RAT priority levels are designated so that a RAT given a higher prioritylevel is detected, another RAT may suspend its usage of the resource.Accordingly, the UE may be required to define when to performtransmission from a resource that may be potentially used in another RATat a high priority. Proposal 6: In the detect-and-vacate operation, itmay be assumed that, in a given set of resources, different RATs mayhave different priority levels. When a RAT having a low priority level(e.g., RAT A) detects a RAT having a higher priority level (e.g., RAT B)in a specific resource set X corresponding to RATs having low prioritylevels, the RAT having a low priority level (e.g., RAT A) may suspendits transmission. Related inquiries (or questions) correspond to whichresource will be used for the transmission of RAT A. More specifically,this corresponds to a case where a predetermined level of waiting timeand reliability requirements are required. In this case, sincesuspending the transmission is not appropriate, a basic assumption thatRAT A corresponds to another resource set Y having a high priority levelmay be made. Therefore, in the point of view of the RAT, the resourceset Y may be used as the basic resource, and resource set X maycorrespond to a type of auxiliary set being occasionally used for anoffload. RAT A may use resource set X only when offloading is required.Otherwise, since the inter-RAT detection is not perfect, interferencemay occur in RAT B. Additionally, considering a limitation in the numberof operational carriers and an overhead/latency during switching andsorting (or alignment) of the operational carriers through the UE,maximum prevention of unnecessary multi-carrier management (oroperation) is required. In case there is no problem of congestion in aresource set of a high priority level RAT, this may indicate that the UEdoes not use a resource set of a low priority level RAT. Proposal 7: Inthe detect-and-vacate operation, it may be assumed that each RAT has aresource set of the highest priority level. It may be considered thatthe UE uses another resource only when congestion is detected from theresource set of the highest priority level. A resource set, wherein theLTE SL V2V has a low priority level, may be configured in multiplecarriers. In this case, the receiving UE may be required to know whichcarrier is being used by the transmitting UE for the purpose ofoffloading. In order to support this operation, the UE may broadcastinformation on the transmission carrier to other UEs located near thecorresponding UE. In order to support the sorting method used in thecarriers that are used throughout all of the UEs, among the carriers,the carrier having the first order may be first considered as thetransmission carrier. In case time is not allowed for the UE to fully(or completely) monitor the switched carrier, a random resourceselection or a limited resource detected, which were discussed for theV2P, may be viewed as fallback operations. Meanwhile, in case each ofthe UEs are equipped with a multi-carrier receiving function and isalready monitoring the candidate carriers, such fallback operation maynot be required. Therefore, an assumed multi-carrier capacity may firstbe discussed. Proposal 8: In case the detect-and-vacate operation isoperated through multiple carrier, discussion is required to be carriedout on how to sort (or align) the transmission carriers among the UEs.3.4. Inter-RAT co-existence in a V2P case In case of the BV2P, the P-UEtransmission and V-UE reception scenario was prioritized during the SIphase. However, in case of the co-existence between the detection-basedRATs, if such co-existence mechanism is also used in the V2P case, thelimited P-UE receiving capability needs to be considered. Although onepossibility is to operate each P-UE so that other RATs can be detectedbefore carrying out the transmission, this will eventually require alarger amount of battery consumption and RX function of a PC5 carrier.Even if a partial sensing operation is carried out, limitations mayexist in that the P-UE may not be capable of detecting the presence ofanother RAT within the subframe that is not monitored. In order toresolve this problem, resource of the eNB may be considered. Each V-UEmay report the detection of another RAT to the eNB along with theposition information of the corresponding V-UE. Accordingly, the eNB mayforward the corresponding information to the P-UE, and, by acquiring aportion of the position information of the related V-UE from theforwarded information, the transmission of the P-UE may be determined.Optionally, the eNB may activate/deactivate a resource poolcorresponding to the P-UEs within the region based on the reportreceived from the V-UEs. Proposal 9: In case the detect-and-vacateoperation is operated for the V2P case, a solution enabling the P-UE torecognize the presence of another RAT may be required. The V-UE reportand eNB forwarding may be considered. 3.5. The above-described proposalsmay be summarized as described below. Proposal 1: An LTE SL V2V designfor the co-existence with a Dedicated Short-Range Communications (DSRC)should consider an extension of the co- existence with the NR V2X.Proposal 2: A RAN1 specification resource may not be required in the“geographical location and database” and “time sharing between GNSStiming- based systems” options. Proposal 3: When the LTE UE senses ahigh energy level from a resource performing no LTE transmission, theLTE UE may detect the presence of another RAT. A “resource having no LTEtransmission” may correspond to a resource that is configured just asthe implicit resources or a resource having no LTE signals discoveredtherein. Proposal 4: Even in case a load corresponding to an LTE SL V2Vis high, a solution may be required in order to ensure a transmissionopportunity of IEEE 802.11p. Proposal 5: When a pre-decided signal isused for an inter-RAT detection, a new LTE SL signal is required to betransmitted from a first and/or final symbol(s) of all subframes fromwhich the UE transmits the PSCCH/PSSCH. Herein, the AGC operation shouldbe ensured in the first symbol, and the TX/RX switching operation andthe absorbing operation of a UL TX timing advance should be ensured inthe last symbol. Proposal 6: In the detect-and-vacate operation, it maybe assumed that, in a given set of resources, different RATs may havedifferent priority levels. Proposal 7: In the detect-and-vacateoperation, it may be assumed that each RAT has a resource set of thehighest priority level. It may be considered that the UE uses anotherresource only when congestion is detected from the resource set of thehighest priority level. Proposal 8: In case the detect-and-vacateoperation is operated through multiple carrier, discussion is requiredto be carried out on how to sort (or align) the transmission carriersamong the UEs. Proposal 9: In case the detect-and-vacate operation isoperated for the V2P case, a solution enabling the P-UE to recognize thepresence of another RAT may be required. The V-UE report and eNBforwarding may be considered.

Since the above-described examples of the co-existence methods may alsobe included as one of the methods for implementing the presentinvention, it will be apparent that the above-described examples can beviewed as other types of co-existence methods. Additionally, althoughthe above-described co-existence methods may be independentlyimplemented, the co-existence methods may be implemented in a combined(or integrated) form of parts of the co-existence methods. For example,although the present invention is described based on a 3GPP LTE systemfor simplicity in the description, the scope of systems in which theco-existence methods can be applied may be extended to diverse systemsother than the 3GPP LTE system.

For example, the co-existence methods according to the present inventionmay also be extendedly applied to D2D communication. Herein, forexample, D2D communication refers to performing communication between aUE and another UE by using a direct wireless channel. And, herein, forexample, although the UE refers to a user device, in case a networkequipment, such as a base station, transmits/receives signals accordingto a communication method performed between UEs, the correspondingnetwork equipment may also be viewed as a type of UE.

Additionally, for example, the co-existence methods according to thepresent invention may also be limitedly applied only in MODE 2 V2Xoperations (and/or MODE 1 V2X operations). Additionally, for example,the co-existence methods according to the present invention may also belimitedly applied only to V-UE(s) (or P-UE(s)) (and/or V2X UE(s) beingequipped with a V2X carrier(/channel(/band)) for a (dedicated) RX(/TX)chain.

Hereinafter, the present invention will be described in detail.

In the following proposed methods, the UE may correspond to a userdevice (or UE) having restricted (or limited) capability. For example,the UE may correspond to a UE having a limited reception(RX)/transmission (TX) chain/circuit capability (and/or a UE having alimited battery capacity(/duration time/consumption)). For example, theUE may correspond to a UE being equipped with only one receivingunit(/transmitting unit), thereby being incapable ofreceiving(/transmitting) a signal according to the WAN communication ofthe first frequency and a signal according to the V2X communication ofthe second frequency at the same time. The UE may correspond to apedestrian UE (P-UE; as a UE carried by a pedestrian, this may also bereferred to as a handheld UE for pedestrians), which has relativelygreater limitation in hardware implementation cost/increase incomplexity/battery power consumption (as comparted to a UE beinginstalled in a vehicle (vehicle-UE (V-UE))).

When the UE performs a V2X message transmission(/reception) operationwithin a V2X carrier or resource pool (a carrier/resource pool havingthe V2X communication set thereto), a method allowing this operation tobe efficiently performed will hereinafter be proposed.

Hereinafter, for simplicity in the description of the proposed method,for example, it will be assumed that a user device P-UE #K has aone-reception (RX) chain/circuit capability and a two-transmission (TX)chain/circuit capability.

Additionally, a situation where the P-UE #K performs WAN DL/ULcommunication in wide area network (WAN) DL/UL carrier #X (this may beinterpreted as carriers having the WAN DL/UL communication configuredthereto) and performs a V2X message transmission(/reception) operationwithin a V2X carrier #Y (at the same time) will be assumed. However, inaddition to the above-described situation, the proposed methods of thepresent invention may also be extendedly applied in other diverse cases(e.g., cases where capabilities exceeding the reception(/transmission)chain/circuit capability of the V2X UE are being required).

It may be interpreted that the P-UE #K does not have a ‘dedicatedreceiving unit(/transmitting unit) (or dedicated RX(/TX) chain/circuit)’within the V2X carrier #Y where the V2X communication is beingperformed. More specifically, it may be interpreted that only the‘TX(/RX) chain/circuit’ exists within the V2X carrier #Y.

A “transmission resource collision avoiding operation (i.e., sensingmethod)” between V2X UEs is more advantageous in enhancing the V2Xcommunication performance as compared to a random method wherein the V2XUEs randomly select/re-select a transmission resource.

The sensing operation may (A) be performed through a decoding of a‘scheduling assignment (SA) channel (e.g., PSCCH) and/or through ameasurement (e.g., ‘PSSCH-RSRP’)’ of a pre-defined channel/referencesignal (RS) (e.g., ‘DM-RS’) within a ‘data channel (e.g., PSSCH)’ thatis interconnected to the (corresponding) decoded PSCCH and/or (b) beperformed through an energy measurement (e.g., ‘S-RSSI’).

Hereinafter, for example, the terms used herein, such ascarrier/band/channel, and so on, may be interpreted as a resource pool.

<Proposed Method #1>

When a P-UE #K (having a limited reception (RX) chain/circuitcapability) performs a V2X message transmission operation within V2Xcarrier #Y, instead of borrowing(/switching) a RX chain/circuit that isused in the WAN downlink reception operation (WAN DL carrier #X)(regardless of the configuration of the sensing operation), the P-UE #Kmay (re-)select a transmission resource (within the V2X carrier #Y) forperforming a V2X message transmission by (always) using a random method.

For example, the V2X message may be (periodically) transmitted based ona cycle period value (that is determined in a higher-level layer (of theUE)) (and/or may be transmitted based on a (re-)selected(/reserved)(periodic) resource (that is (re-) selected(/reserved) based on thecorresponding cycle period value). Herein, for example, when performing(transport block (TB) related) (data/scheduling assignment) transmissionresource (re-)selection(/reservation), with the exception for a subframeto which the (TB related) (data/scheduling assignment) transmissionresource, which is (re-)selected(/reserved) at a previous (cycleperiod(/transmission resource (re-)selection(/reservation))) time point,the P-UE #K may limitedly perform (re-)selection(/reservation) in theremaining subframes (this has the effect of resolving the half duplexproblem).

For example, when the P-UE #K performs the (re-)selection(/reservation)of the transmission resource, may select specific subframe(s), from(re-)selection(/reservation) candidate resources configured of 100subframes (wherein it is assumed that the 100 subframes are indexed from0 to 99), and may then transmit a V2X message. If the P-UE #K hasselected an N^(th) subframe (from the (re-)selection(/reservation)candidate resources) at a previous transmission resource(re-)selection(/reservation) time point, the P-UE #K may (randomly)select a specific subframe among the remaining subframes excluding theN^(th) subframe (from the (re-)selection(/reservation) candidateresources) at a next transmission resource (re-)selection(/reservation)time point.

Herein, for example, the P-UE #K may perform a V2X message transmissionoperation by using a ‘UU interface’ or a WAN uplink (UL) (in case thesensing operation is configured). Such operation may also be interpretedas a switching operation between the PC5 and UU (or WAN uplink).

<Proposed Method #2>

The P-UE #K (having a limited reception (RX) chain/circuit capability)may assume that a “sensing gap(/sensing resource) or receivinggap(/receiving resource) or a partial sensing gap(/partial sensingresource)” of a pattern, which is configured (or determined) or signaledin advance (by the network), (e.g., ‘bitmap/cycle period/offset’) existswithin a time/frequency resource that is configured (or determined) orsignaled in advance (prior to performing the V2X message transmission(resource (re-)selection(/reservation)) operation) (e.g., atime/frequency resource preceding the V2X transmission resource pooland/or a time/frequency resource prior to the (scheduling assignment)cycle period(/time point) in/at which the V2X message transmission(resource (re-)selection(/reservation)) operation is to be performed).Herein, for example, the “sensing gap or receiving gap” wording may alsobe referred to as a partial sensing gap (hereinafter equally applied orused). Herein, for example, the “sensing gap” may refer to a resourcethat should perform sensing in order to (re-) select(/reserve) theresource (e.g., subframe) that is to be used by the UE for the V2Xsignal transmission, and, in this aspect, the sensing gap may also bereferred to as a sensing resource. Similarly, the “receiving gap” mayrefer to a resource that should receive(/decode) a signal(/channel) inorder to allow the UE to perform the sensing operation (and/or aresource that should perform PSSCH-RSRP/S-RSSI measurement), and, inthis aspect, the receiving gap may also be referred to as a receiving.Additionally, a “partial sensing gap” may refer to a (partial) resourcethat is configured to perform the sensing operation, and, in thisaspect, the partial sensing gap may also be referred to as a partialsensing resource.

Within the sensing gap(/resource) (or receiving gap(/resource)/partialsensing gap(/resource), hereinafter equally applied or used), the P-UE#K may perform switching(/borrowing) of its own reception chain/circuit,which is used for the WAN downlink reception operation (WAN DL carrier#X) and/or the sensing operation (or partial sensing operation). Herein,for example, the sensing operation may include at least one of 1) anoperation that acquires information on resources that are occupied byperforming decoding of the scheduling assignment channels beingtransmitted by another V2X UE, and 2) an operation that acquiresinformation on resources having a high interference level as a result ofperforming the (energy) measurement operation (e.g., PSSCH-RSRP, S-RSSI)corresponding to a pre-defined channel/reference signal or resourcesbeing occupied by another V2X UE.

By performing the above-described sensing operation, the avoidance oftransmission resource collision with other V2X UEs becomes possible.

FIG. 10 is an example of a V2X transmission resource(re-)selecting(/reserving) method according to a partial sensingoperation of <Proposed Method #2>.

Referring to FIG. 10, (re-)selection(/reservation) of the resource forV2X signal transmission may be determined(/triggered) for the UE (P-UE,hereinafter equally applied or used) (according to whether or not apre-defined condition is satisfied). For example, it will be assumedthat the transmission resource (re-)selection(/reservation) is triggeredin subframe #m. In this case, the UE may (re-)select(/reserve) aresource for the V2X signal transmission in a section starting fromsubframe #m+T1 to subframe #m+T2. The section starting from subframe#m+T1 to subframe #m+T2 will hereinafter be referred to as a selectionwindow. The selection window may, for example, be configured of 100consecutive subframes.

In the selection window, the UE may select a minimum of Y number ofsubframes as the candidate resources. More specifically, the UE may haveto consider a minimum of Y number of subframes as the candidateresources within the selection window. Herein, the Y value maycorrespond to a pre-configured value or may correspond to a value thatis configured (or determined) by the network. Herein, however, how toselect the Y number of subframes within the selection window maycorrespond to an issue of UE implementation. More specifically, if, forexample, the Y value is given as 50, the UE may decide which 50subframes it will be selecting among the 100 subframes configuring theselection window. For example, among the 100 subframes, the UE mayselect 50 subframes being indexed with odd numbers, or the UE may select50 subframes being indexed with even numbers. Alternatively, the UE mayselect 50 subframes according to a random rule.

Meanwhile, in order to (re-)select(/reserve) a specific subframe, e.g.,subframe #N (SF #N) as the V2X transmission subframe that can transmitthe V2X signal, among the Y number of subframes, the UE may have tosense at least one subframe that is linked or related to subframe #N.Herein, a (total) subframe section that is defined for the sensingprocess will be referred to as a sensing window, and the sensing windowmay, for example, be configured of 1,000 subframes. More specifically,the sensing window may be configured of 1,000 milliseconds (ms) or 1second. For example, within the sensing window, the UE may sensesubframes corresponding to subframe #N−100*k (wherein k may correspondto a set of elements corresponding to a range of [1, 10] and maycorrespond to a value that is pre-determined or configured by thenetwork).

FIG. 10 shows an example where the k value corresponds to {1, 3, 5, 7,10}. More specifically, the UE may sense subframes #N-1000, #N-700,#N-500, #N-300, and #N-100 so as to estimate/determine whether or notsubframe #N is being used by another V2X UE (and/or whether or not ahigh interference level exists (or whether or not an interference levelbeing greater than or equal to a pre-configured(/signaled) thresholdvalue exists within subframe #N) and may then (finally) select subframe#N according to the estimated/determined result. Since the P-UE issensitive to the consumption of batter power as compared to the V-UE,instead of sensing all of the subframes existing in the sensing window,the P-UE may sense only part of the subframes, i.e., the P-UE mayperform partial sensing.

FIG. 11 is an example of a V2X transmission subframe(/resource) (re-)determining(/selecting(/reserving)) method according to the <ProposedMethod #2>.

Referring to FIG. 11, the UE receives pattern information that is usedfor determining a (partial) sensing pattern (S191). The patterninformation may be provided by a network through an RRC (or SIB)message, and so on.

The following table shows an example of the pattern information.

TABLE 4 --ASN1START SL-P2X-SensingConfig-r14 : := SEQUENCE {minNumCandidateSF-r14 INTEGER (1. . 13), gapCandidateSensing-r14 BITSTRING (SIZE (10)) } --ASN1STOP

In the table presented above, ‘minNumCandidateSF’ represents a minimumnumber of subframes that must be included in the possible candidateresources. As described above, the UE is required to consider theminimum Y number of subframes as the candidate resources within aselection window. At this point, ‘minNumCandidateSF’ may indicate the Yvalue.

When a subframe is considered as a candidate resource,‘gapCandidateSensing’ indicates which subframe should be sensed. Asdescribed above, in case a specific subframe, e.g., subframe #N (SF #N)is selected as a candidate resource among the Y number of subframes,subframes corresponding to subframe #N−100*k should be sensed from thesensing window. And, in this case, ‘gapCandidateSensing’ may indicatethe k value through a 10-bit bit string. For example, in case the kvalue corresponds to {1, 3, 5, 7, 10}, the ‘gapCandidateSensing’ may beindicated as “1001010101”.

Among the subframes within the sensing window, the UE senses part of thedetermined subframes based on the pattern information (S192). Morespecifically, the UE performs partial sensing. Partial sensing hasalready been described above in detail with reference to FIG. 10.

The UE selects a specific subframe within the selection window as theV2X transmission subframe based on the above-described sensing operation(S193).

FIG. 12 is an example of a communication method between a pedestrian UE(P-UE), a vehicle UE (V-UE), and a network according to the <ProposedMethod #2>. Herein, for example, although a situation where the P-UEtransmits a V2X signal to the V-UE is assumed in FIG. 12, generally, theV2X signal being transmitted by the P-UE may set other entities (e.g.,P-UE, V-UE, (UE-type) RSU, and so on) as well as the V-UE as its target.

Referring to FIG. 12, the network provides (sensing) pattern informationto the pedestrian UE (S201). The pattern information has already beendescribed above in detail with reference to Table 4.

The P-UE performs partial sensing based on the (sensing) patterninformation and selects a V2X transmission subframe in accordance withthe partial sensing result (S202).

The P-UE transmits a V2X signal from the selected V2X transmissionsubframe (S203).

<Proposed Method #3>

(A pedestrian UE having a limited reception chain/circuit capability,such as) P-UE #K may report information on a sensing gap(/resource) orreceiving gap(/resource) or partial sensing gap(/resource) having itspreferred format or pattern (to the network through the WAN uplink).Herein, for example, the corresponding sensing gap(/resource) orreceiving gap(/resource) or partial sensing gap(/resource) informationmay be configured to have a bitmap format and/or a format informing acycle period/offset value (of the sensing gap(/resource)(/receivinggap(/resource)/partial sensing gap(/resource))).

The preferred sensing gap(/resource)(/receiving gap(/resource)/partialsensing gap(/resource)) format/pattern may include a partialtime/frequency resource region having a relatively low energymeasurement result value (and/or a ‘congestion level’ result value),after the P-UE #K performs the measurement(/sensing) operation (withinthe pre-configured or pre-signaled time/frequency resource section).

<Proposed Method #4>

(In case the above-described Proposed Method #3 is applied,) If thesensing gap(/resource) (or receiving gap(/resource) or partial sensinggap(/resource)) pattern (received from the base station) fails to coverall of the (previous) time/frequency resource(/pool) region thatrequires a sensing operation (related to the pool(/resource) in whichthe V2X message transmission operation is to be performed) (or fails tocover a region corresponding to a pre-configured(/signaled) (threshold)ratio value or more) (e.g., in case the corresponding sensinggap(/resource)(/receiving gap(/resource)/partial sensing gap(/resource))pattern covers only part of the resources(/subframes) within the sensingwindow), the corresponding V2X message transmission operation may beperformed according to the following rule.

Herein, for example, when the V2X message transmission operation isperformed within V2X transmission resource pool #J (which isinterconnected with the scheduling assignment pool(/cycle period) #J),the sensing operation for the corresponding V2X transmission resourcepool #J may be performed within the previous time/frequency resource(e.g., within V2X transmission resource pool #(J-1) (which isinterconnected with the scheduling assignment pool(/cycle period)#(J-1)). As described above, the sensing gap(/resource) (or receivinggap(/resource)) based sensing operation may be interpreted as a ‘partialsensing operation’.

Example #4-1

Within the sensing gap(/resource) (or receiving gap(/resource) orpartial sensing gap(/resource) (hereinafter equally applied or used))pattern (received from the base station), a transmission resourcecollision avoiding operation with other V2X UEs may be performed byusing only the acquired sensing information (e.g., information on theresource occupied by another V2X UE, information on a resource having ahigh interference level).

For example, (in case another UE repeats the usage of the resource at aconsistent cycle period, if the sensing gap(/resource)(/receivinggap(/resource)/partial sensing gap(/resource)) fails to cover all of the(one) repetition cycle period (or sensing window),) the P-UE may beoperated so as to be capable of (re-)selecting(/reserving) its optimaltransmission resource only within the resource in which the sensing hasbeen performed through the sensing gap(/resource)(/receivinggap(/resource)/partial sensing gap(/resource)).

For example, in case of (re-)selecting(/reserving) a resource having alowest energy level, the (re-)selection(/reservation) may be limited to(re-)selecting(/reserving) a resource having the lowest energy levelamong the resources belonging to the sensing gap(/resource) (orreceiving gap(/resource) or partial sensing gap(/resource)).

For example, in case of determining a resource occupied by another UEthrough the scheduling assignment channel decoding of the other UE, the(re-)selection(/reservation) may be limited to(re-)selecting(/reserving) only a ‘data resource’ that can be scheduledby a scheduling resource that belongs to the sensinggap(/resource)(/receiving gap(/resource)/partial sensinggap(/resource)).

At the current transmission resource (re-)selecting(/reserving) (cycleperiod) time point, when performing (transmission block related) (dataor scheduling assignment, hereinafter equally applied or used)transmission resource (re-)selection(/reservation), the P-UE #K maylimitedly perform (re-)selection(/reservation) in the remainingsubframes after excluding the subframe to which the (transmission blockrelated) (data or scheduling assignment) transmission resource belongs,wherein the corresponding transmission resource has been(re-)selected(/reserved) at the previous (re-)selecting(/reserving)(cycle period) time point. Accordingly, the half duplex problem may beresolved (under the environment of an incomplete sensing informationbased transmission resource (re-)selecting(/reserving) operation).Herein, the half duplex problem refers to a case where, since the UE isincapable of transmitting and receiving signals at the same time, incase of repeatedly using the same resource (e.g., frequency resource)for the transmission/reception of signals, the transmission/reception ofsignals cannot be repeatedly performed within the correspondingresource.

FIG. 13 shows an example of a method for (re-)selecting(/reserving) aV2X transmission resource according to Example #4-1.

Referring to FIG. 13, at a first transmission resource(re-)selecting(/reserving) time point(/cycle period), the UE may selecta first subframe (223) from a first selection window (222). Herein, theinterconnected subframes that need to perform sensing when selecting thefirst subframe (223) are indicated as the sensing resources within afirst sensing window (221).

At a first transmission resource (re-)selecting(/reserving) timepoint(/cycle period), the UE may select a second subframe (226) from asecond selection window (225). At this point the second subframe (226)corresponds to a subframe that does not overlap with a subframe (227)having the same position(/order) as the first subframe (223) (within theselection window). More specifically, when selecting the second subframe(226), with the exception of the subframe having the sameposition/subframe order(/number) as the first subframe (223) within thesecond selection window, the second subframe (226) is selected from theremaining subframes. The interconnected subframes that are required toperform sensing in order to select the second subframe (226) may beindicates as sensing resources within the second sensing window (224).

According to the above-described method, since different resources areselected from each of the first selection window and the secondselection window, the half duplex problem may be resolved.

The sensing resource that is interconnected(/linked) to the excludedsubframe(/resource) (even if the sensing resource is included in thesensing gap(/resource)(/receiving gap(/resource)/partial sensinggap(/resource))) may omit the sensing operation and/or may be avoidedfrom being included in the sensing gap (by having the P-UE #K report therelated information to the base station).

FIG. 14 shows an example of a method for (re-)selecting(/reserving) aV2X transmission resource according to Example #4-1.

Referring to FIG. 14, the UE may select a second subframe, which doesnot overlap with a first subframe being selected from a first selectionwindow, from a second selection window as a candidate resource (S211).

The UE senses the subframes being linked/interconnected to the secondsubframe within the second sensing window (S212).

The UE may select the second subframe as the V2X transmission subframeaccording to the sensing result (S213).

Example #4-2

For example, the transmission resource (re-)selection operation may alsobe performed by using another method that is defined or signaled inadvance, for example, a random method.

As another example, the V2X message transmission operation may also beperformed by using the ‘UU interface’ or WAN uplink. Such operation mayalso be interpreted as switching between the PC5 and the UU (or WANuplink).

Example #4-3

If the P-UE #K has failed to receive the sensing gap(/resource) (orreceiving gap(/resource) or partial sensing gap(/resource)), the P-UE #Kmay (re-) select(/reserve) a transmission resource by using anothermethod(/fallback method) (e.g., random method) that is defined orsignaled in advance (even if the sensing operation has already beenconfigured). Alternatively, the V2X message transmission operation mayalso be performed by using the ‘UU interface’ (or WAN uplink).

[Proposed Method #5]

If the P-UE is set to perform the sensing operation for an excessivelylong period of time, for example, (due to WAN DL RX chain/circuitswitching) the WAN downlink receiving performance may be degraded and/orthis may be disadvantageous in the aspect of battery power consumption.Alternatively, in case the P-UE is set to perform the (partial) sensingoperation only for a fixed (or (semi-)static) time/frequency resourceregion for a short or limited period of time, for example, degradationmay occur in the accuracy of energy sensing and the transmissionresource collision avoidance performance. Considering theabove-described details, settings may be made so that the (partial)sensing operation related parameters, e.g., a length of a section duringwhich the (partial) sensing operation is performed (sensing duration), a(partial) sensing pattern (this indicates a format(/pattern)/cycleperiod/offset according to which the sensing operation is beingperformed, and this pattern may be provided in a bitmap format), and soon, can be processed with ‘(time) hopping’ and/or ‘randomization’according to a pre-defined rule.

The ‘(time) hopping (pattern)’ and/or the ‘randomization (pattern)’ maybe randomized among V2X UEs each being different from one another. Forexample, the ‘(time) hopping (pattern)’ and/or the ‘randomization(pattern)’ may be randomized by a function that is defined in advancebased on at least one of multiple input parameters, such as an ID of atransmitting UE, an ID of a receiving UE, a (cycle period) index (of aresource/pool) in which the V2X message transmission operation is beingperformed, a scheduling (cycle period) index (of a resource/pool), andso on.

Meanwhile, (although the UE has a reception chain/circuit,) the UE mayonly have a limited TX chain/circuit capability for a plurality ofcarriers. In this case, the UE may perform the sensing operation withininterconnected sensing resources (being interconnected with resourcesbelonging to a transmission gap) among the resources belonging to a“transmission gap (TX gap)” that is defined or signaled in advance. And,then, the UE may limitedly (re-)select its own optimal transmissionresource based on the result of the sensing operation.

The transmission gap may be interpreted as a resource region wherein theV2X message transmission has a relatively higher priority level ascompared to the WAN uplink transmission.

In this case, by having the V2X UE (re-)select(/reserve) resource(s)that do(es) not belong to the transmission gap for the purpose of V2Xmessage transmission, due to an overlapping with the WAN uplinktransmission (within the same carrier (or different carriers)), theproblem wherein the V2X message transmission is omitted (or dropped)(and/or the transmission power is assigned at a lower priority level)may be resolved.

The P-UE #K having a limited transmission chain/circuit capacity mayreport transmission gap information of a format(/pattern) that ispreferred by the P-UE #K (e.g., ‘bitmap/cycle period/offset’) to thenetwork (through the WAN uplink).

The preferred transmission gap format(/pattern) may include a (partial)(time(/frequency)) resource region having a relatively low (energy)measurement result value (and/or ‘congestion level’ result value) afterthe P-UE #K has performed the measurement(/sensing) operation (within atime(/frequency) resource (section) that is configured(/signaled) inadvance).

Alternatively, the transmission gap may be commonly applied amongcarriers having the V2X communication performed therein. In case thetransmission gap is configured(/applied) (commonly among the carriers),when ‘WAN uplink transmission’ and ‘V2X message transmission’ areperformed at the same time within different carriers, or when the ‘WANuplink transmission’ and the ‘V2X message transmission’ partiallyoverlap one another within the time region, since a transmission powerdistribution of a higher priority level is assigned to the ‘WAN uplinktransmission’, the generated ‘problem of degradation in the V2Xcommunication performance’ may be resolved.

In other words, in case the ‘WAN uplink transmission’ and the ‘V2Xmessage transmission’ are transmitted to (partially or fully) overlapone another within different carriers, this may also be interpreted asthe transmission gap assigning(/distributing) transmission power havinga relatively higher priority level to the V2X message transmission ascompared to the WAN uplink transmission. In case of applying theabove-described rule, by assigning(/distributing) a low V2X messagetransmission related transmission power, the problem of performancedegradation in the V2X communication (or public safety (PS)communication) may be resolved.

Alternatively, in the point of view of a V2X UE, in case the ‘WAN uplinktransmission’ and the ‘V2X message transmission’ are performed at thesame time within different carriers or have at least a portion of bothtransmissions overlap one another in the time region, if thecorresponding section is configured as the transmission gap, atransmission power having a relatively higher priority level may beassigned(/distributed) to the V2X message transmission as compared tothe WAN uplink transmission. Herein, a pre-defined or signals minimumvalue of the transmission power value may be ensured to the WAN uplinktransmission. In case the above-described rule is applied, a limitedlevel of the performance related to the WAN uplink communication may beensured.

Hereinafter, a V2X UE, e.g., V-UE and/or P-UE that can (partially)perform the (scheduling assignment decoding/energy measurement based)sensing operation will be referred to as a type #A_UE. Morespecifically, the type #A_UE corresponds to a UE that can perform(partial) sensing. Additionally, a V2X UE (e.g., P-UE) that cannotperform the (scheduling assignment decoding/energy measurement based)sensing operation will be referred to as a type #B_UE. Morespecifically, the type #B_UE corresponds to a UE that cannot perform(partial) sensing.

Meanwhile, diverse types of V2X transmission resource pools may exist.

FIG. 15 shows an example of the V2X transmission resource pool types.

Referring to FIG. 15 (a), V2X transmission resource pool #A maycorrespond to the resource pool allowing only the (partial) sensing. Inthe V2X transmission resource pool #A, the UE is required to select theV2X transmission resource after performing the (partial) sensing, and,in this case, random selection may not be allowed. The V2X transmissionresource that is selected by (partial) sensing is semi-persistentlymaintained at constant cycle period, as shown in FIG. 15 (a).

In order to allow the UE to perform the V2X message transmission withinthe V2X transmission resource pool #A, the base station may configuresettings so that the (scheduling assignment decoding/energy measurementbased) sensing operation can be (partially) performed. This may beinterpreted that the ‘random selection’ of the transmission resource isnot allowed within the V2X transmission resource pool #A, and that(only) the ‘(partial) sensing’ based transmission resource selection isperformed(/allowed to be performed). The settings may be made by thebase station.

Referring to FIG. 15 (b), V2X transmission resource pool #B maycorrespond to the resource pool allowing only the random selection. Inthe V2X transmission resource pool #B, the UE does not perform the(partial) sensing and may randomly select the V2X transmission resourcefrom the selection window. Herein, for example, unlike the resource poolthat only allows the (partial) sensing, configuration(/signaling) may beperformed so that the selected resource can be prevented from beingsemi-persistently reserved.

In order to allow the UE to perform the V2X message transmissionoperation within the V2X transmission resource pool #B, the base stationmay configure settings so that the (scheduling assignmentdecoding/energy measurement based) sensing operation is not performed.This may be interpreted that (only) the ‘random selection’ isperformed(/allowed) and/or the ‘(partial) sensing’ based transmissionresource selection is not allowed within the V2X transmission resourcepool #B.

Meanwhile, although it is not shown in FIG. 15, a resource pool capableof performing both the (partial) sensing and the random selection mayexist. The base station may notify that the V2X resource may be selectedby using either one of the (partial) sensing method and the randomselection method (for implementing the UE) in the above-describedresource pool

FIG. 16 is an example of a method for selecting a V2X resource pool in asituation where multiple types of resource pools exist.

Referring to FIG. 16, the UE receives type information notifying a typeof the resource pool (S300).

The following table shows an example of the type information.

TABLE 5 --ASNISTART SL-P2X-ResourcSelectionConfig-r14 : := SEQUENCE {partialSensing-r14 ENUMERATeD {true} OPTIONAL, -- Need ORrandomSelection-r14 ENUMERATED {true} OPTIONAL -- Need OR. } --ASN1STOP

In the Table presented above, ‘partialSensing’ indicates that partialsensing is allowed in the corresponding resource pool for the UE toperform resource selection. ‘randomSelection’ indicates that, when theUE selects a resource in the corresponding resource pool, randomselection is allowed. More specifically, by indicating by which methodthe UE can select a V2X transmission resource from a specific resourcepool, the ‘randomSelection’ may indicate (or inform) the type of thespecific resource pool (e.g., a resource pool that only allows partialsensing based transmission resource selection, a resource pool that onlyallows random selection based transmission resource selection, aresource pool that allows both partial sensing based and randomselection based transmission resource selection).

The UE performs at least one of random selection and resource selectionthat is based on partial sensing within the resource pool based on thetype information (S310).

For example, through a pre-defined signaling (of the type information),the base station may allow a type #A UE to perform a (schedulingassignment decoding/energy measurement based) sensing operation basedtransmission resource assignment/scheduling, a V2X message transmissionoperation, and so on, within the V2X transmission resource pool #A, andthe base station may allow a type #A UE to perform transmission resourceassignment/scheduling without the (scheduling assignment decoding/energymeasurement based) sensing operation (or a random selection basedtransmission resource assignment/scheduling), a V2X message transmissionoperation, and so on, within the V2X transmission resource pool #B.

Even if a UE is capable of performing the (scheduling assignmentdecoding/energy measurement based) sensing operation, (in addition tothe (scheduling assignment decoding/energy measurement based) sensingoperation based transmission resource assignment/scheduling, a V2Xmessage transmission operation, and so on (within the V2X transmissionresource pool #A),) transmission resource assignment/scheduling withoutthe (scheduling assignment decoding/energy measurement based) sensingoperation, a V2X message transmission operation (e.g., the randomselection method), and so on, (within the V2X transmission resource pool#B) may be allowed (by the base station through a signaling that ispre-defined in advance). Herein, for example, ((however,) if a V2Xtransmission resource pool that is required to perform/apply the(scheduling assignment decoding/energy measurement based) sensingoperation exists among the V2X transmission resource pools,) the type #AUE may be set (to be capable of using a V2X transmission resource poolthat (absolutely or (necessarily)) required to perform/apply the(scheduling assignment decoding/energy measurement based) sensingoperation and/or) to be capable of performing (scheduling assignmentdecoding/energy measurement based) sensing operation based transmissionresource assignment/scheduling, a V2X message transmission operation,and so on (within the V2X transmission resource pool #A).

In order words, this may be interpreted that the usage of a resource(V2X transmission resource pool) designated for a V2X UE having arelatively poor sensing-related capability is limited(/prohibited) to aV2X UE having a relatively excellent sensing-related capability. And/Or,this may be interpreted that, by allowing a V2X UE having a relativelyexcellent sensing-related capability and a V2X UE having a relativelypoor sensing-related capability to use(/share) the same V2X transmissionresource pool, the degradation in the V2X communication performance ofthe V2X UE having a relatively excellent sensing-related capability,which is caused by a collision between transmission resources, may beprevented.

By performing the pre-defined signaling, the base station may notify thetype #B UE whether the ‘random selection’ operation of the transmissionresource is to be performed(/allowed) only in the V2X transmissionresource pool #B or whether the ‘random selection’ operation of thetransmission resource is to be performed(/allowed) also in the V2Xtransmission resource pool #A.

In the V2X transmission resource pool #A, configuration(/signaling) maybe performed so that, after performing the ‘(partial) sensing’ basedtransmission resource selection, the selected transmission resource canbe maintained(/reserved) for a predetermined period of time. And/Or, inthe V2X transmission resource pool #B, configuration(/signaling) may beperformed so that, after performing the transmission resource ‘randomselection’, the selected transmission resource is notmaintained(/reserved) for a predetermined period of time. And/Or, in theV2X transmission resource pool #B, configuration(/signaling) may beperformed so that, after a V2X UE (e.g., P-UE only) having a ‘(partial)sensing’ capability (and/or an RX chain/circuit capability) (and/orswitching(/borrowing) an ‘RX chain’ being used for the WAN downlinkreception performs ‘random selection’ of the transmission resource, theselected transmission resource can be maintained(/reserved) for apredetermined period of time.

For each V2X transmission resource pool, configuration/signaling may beperformed so as to indicate that the corresponding resource pool isbeing shared in the transmission between which particular V2X UE type.For example, although a specific resource pool is configured(/signaled)so as to be shared between a V-UE and a P-UE, another resource pool maybe configured(/signaled) so as to be used only by a V-UE (or a P-UE).And/Or, configuration/signaling may be performed so as to indicatewhether the (P-UE related) resource pool, wherein the ‘random selection’is allowed, partially or fully overlaps with a ‘(partial) sensing’ basedresource pool (being used by the V-UE) (e.g., in case a resource poolwherein ‘random selection’ is allowed and a ‘(partial) sensing’ basedresource pool (fully) overlap, the corresponding resource pool may beinterpreted as a resource pool wherein ‘random selection’ and ‘(partial)sensing’ based resource selection are both (or simultaneously) allowed).

Whether a random selection is allowed in a specific resource pool and/orV2X carrier or whether a sensing-based selection is allowed in thespecific resource pool and/or V2X carrier may be explicitly indicatedthrough the type information, as described above, this may also beimplicitly determined by a range value of a pre-configured orpre-signaled specific parameter (hereinafter referred to as an I_value).

For example, in case configuration/signaling is made so as to preventthe parameter within a specific resource pool (and/or (V2X) carrier)from selecting(/allowing) remaining values excluding the value ‘0’, thecorresponding specific resource pool may be interpreted as a resourcepool that is configured(/signaled) to be used only by the UE (e.g.,P-UE) performing ‘random selection’ of transmission resources.

Meanwhile, the specific resource pool may be configured to be sharedbetween the transmission of the V-UE and the P-UE, and/orconfiguration(/signaling) may be performed so that the (P-UE related)resource pool wherein the ‘random selection’ is allowed and the‘(partial) sensing’ based resource pool (being used by the V-UE) canpartially or fully overlap with one another. In this case, settings maybe made so that the (P-)UE performing the ‘random selection’ operationcan maintain(/reserve) the transmission resource that is selected by‘random selection’ within the corresponding resource pool for apredetermined period of time. Alternatively, (in case a specificresource pool is not configured to be shared between the transmission ofthe V-UE and the P-UE, and/or in case configuration(/signaling) is notperformed so that the (P-UE related) resource pool wherein the ‘randomselection’ is allowed and the ‘(partial) sensing’ based resource pool(being used by the V-UE) can partially or fully overlap with oneanother) settings may be made so that the (P-)UE performing the ‘randomselection’ operation does not maintain(/reserve) the ‘random selection’transmission resource within the corresponding resource pool for apredetermined period of time.

FIG. 17 shows an exemplary operation of a UE that has selected aresource by using the random selection method within a resource poolwherein the (partial) sensing is allowed.

For diverse reasons, the UE may select a V2X transmission resource (312)from the resource pool, wherein the (partial) sensing is allowed,through random selection. For example, in case the resource pool whereinthe (partial) sensing is allowed overlaps with the resource pool whereinrandom selection is allowed (and/or in case both random selection and(partial) sensing are both allowed within a specific resource pool), theUE may select the V2X transmission resource by performing randomselection from the resource pool wherein the (partial) sensing isallowed.

In this case, the UE may semi-persistently reserve resources (313)having the same frequency as the V2X transmission resource (312). Morespecifically, the randomly selected resources are repeatedly reserved ata predetermined cycle period throughout a specific section. Although theUE has actually selected the resource by using the random selectionmethod, in case the resource pool from which the resource is selectedoverlaps with the resource pool wherein (partial) sensing is allowed(and/or in case the resource pool from which the resource is selectedallows both random selection and (partial sensing)), it may beinterpreted that the UE performs similar operations as a UE (performing(partial) sensing operation) in a resource pool, wherein (partial)sensing is allowed.

Meanwhile, a same rule(/method) as the type #A UE (or type #B UE) may beapplied to a V2X UE (e.g., P-UE) (limited(/partial) sensing_UE) that canperform a (scheduling assignment decoding/energy measurement based)sensing operation only within a pre-configured(/signaled) limitedtime(/frequency) resource section(/region).

Alternatively, in order to allow the type #A UE to perform the V2Xmessage transmission operation within the V2X transmission resourcepool, the type #A UE may be configured not to perform (or to perform)the (scheduling assignment decoding/energy measurement based) sensingoperation.

For example, it is difficult for P-UE(s) corresponding to (A) a ‘limitedsensing_UE’ format and/or (B) a ‘type #B_UE’ format and/or (C) a‘limited RX chain/circuit’ (or ‘no RX chain/circuit’) format (e.g., incase a ‘dedicated RX chain/circuit’ does not exist (or in case only the‘TX chain/circuit’ exists) within V2X carrier #Y in which the V2Xcommunication is being performed) to determine (efficiently or within ashort period of time) whether other V2X UE(s) (e.g., ‘V-UE(s)’) locatedin the surrounding areas of the P-UE(s) (or being adjacent to theP-UE(s)) perform(s) an ‘ITS (sidelink) service (related V2X message TXoperation)’ and/or ‘public safety (PS) service (related V2X message TXoperation)’, and so on.

Therefore, by applying (part of) the following methods, theabove-described problems may be resolved(/relieved).

For example, (part of) the following methods may also be (extendedly)used in order to allow the efficiently P-UE(s) of the above-described‘(limited) capability(/chain/circuit)’ (e.g., a ‘limited sensing_UE’format, a ‘type #BUE’ format, a ‘limited RX chain/circuit’ format (or a‘no RX chain/circuit’ format or a format having only a ‘TXchain/circuit’)) to determine(/detect) whether the ‘other communication’(e.g., ‘DSRC/IEEE 802.1 ip service’, ‘(other numerology based) NR eV2Xservice’) exists within a proximate distance within the samechannel(/band/carrier) (where the V2X communication is performed).

Herein, for example, the P-UE(s), which has/have determined the presenceof the ‘other communication’ (within a proximate distance within thesame channel(/band/carrier) (where the V2X communication is performed)),efficiently co-exist(s) according to (part of) a rule that is describedin the above-described ‘proposed co-existence method’ (mostparticularly, details are described in the <method allowing the ‘V2Xcommunication’ and the ‘other communication’ to co-exist>).

Hereinafter, referring to the drawings, a method of determining (ordetecting) that another communication is being performed within aVehicle to X (V2X) carrier, deciding a V2X message transmission resourcebased on the detected result, and transmitting the V2X message withinthe transmission resource, which is performed by a P-UE, i.e., (A) a UEhaving insufficient (or limited) sensing capability (e.g., theabove-described ‘limited sensing_UE’), or (B) a UE having no sensingcapability (e.g., the above-described ‘type #BUE’), or (C) a UE having alimited RX chain/circuit, since a ‘dedicated RX chain/circuit’ does notexist within a V2X carrier #Y, wherein the V2X communication is beingperformed (e.g., the above-described ‘limited RX chain/circuit’), willbe described in more detail with reference to the accompanying drawing.

FIG. 18 is a flow chart showing a method for transmitting a V2X messageperformed by a UE having a limited reception capability according to anexemplary embodiment of the present invention.

According to FIG. 18, the UE may receive information indicating thatanother communication is being performed(/detected) within a Vehicle toX (V2X) carrier (S1010). At this point, the UE having a limitedcapability of detecting the performance of another communication maycorrespond to a UE having a limited sensing capability, a UE having nosensing capability, or a UE having no V2X resource dedicated receptionchain, and, as described above, the UE may correspond to a P-UE.

Herein, when receiving the information indicating that anothercommunication is being performed(/detected) within a Vehicle to X (V2X)carrier, the UE may (A) receive the corresponding information from otherV2X UEs, or (B) receive the corresponding information from the basestation. At this point, the information indicating that anothercommunication is being performed(/detected) within the V2X resource maycorrespond to information indicating a type of sidelink service that isbeing performed within the V2X resource. Additionally, the informationindicating that another communication is being performed(/detected)within the V2X resource may correspond to information indicating whetheror not the service being performed within the V2X resource correspondsto a public safety (PB) service. At this point, the informationindicating that another communication is being performed(/detected)within the V2X resource may correspond to information indicating whetheror not a communication that is based on a radio access technology (RAT)other than the RAT of the V2X communication is being performed withinthe V2X resource.

More specifically,

[Proposed Method #6]

(A) Other V2X UE(s) (e.g., ‘V-UE(s)’) and/or (B) a (serving) basestation (being located near the P-UE(s) or (being adjacent to theP-UE(s)) may be configured to notify information, such as an ‘ITSservice type(/content)’ (currently) being operated (or detected) and/or‘whether or not the service correspond to a PS (or non-PS) service’(and/or ‘whether or not another communication (e.g., ‘DSRC/IEEE 802.11pservice’, ‘(other numerology based) NR eV2X service’) exists’), and soon, (to the P-UE(s)) (through a pre-configured(/signaled) channel).

Herein, for example, such rule may be useful for a case where theP-UE(s) has/have difficulty in determining the corresponding informationby using a ‘(sidelink) synchronization signal (SLSS)’ (e.g., a casewhere an ‘ITS service type(/content)’ and/or ‘information related towhether or not the service corresponds to a PS (or non-PS) service’is/are mapped to an ‘SLSS sequence(/ID)’ (and/or a case where different‘SLSS sequences(/IDs)’ are used for each service(/communication))(and/or a ‘PSBCH’ (e.g., a case where such information is signaledthrough a specific (reserved) field within the ‘PSBCH’) and/or in a casewhere a ‘sidelink (dedicated) RX chain/circuit’ does not exist. Herein,for example, the ‘SLSS’ wording may also be interpreted as ‘PSSS’ (or‘SSSS’).

[Proposed Method #7]

For example, in case the ‘service type(/content) (information)’ (e.g.,information on the ‘ITS service type’ and/or information on ‘whether ornot the service corresponds to a PS (or non-PS) service’, and so on) ismapped to the ‘SLSS sequence(/ID)’ (and/or in case different ‘SLSSsequences(/IDs)’ are used for each service(/communication)), (A) OtherV2X UE(s) (e.g., ‘V-UE(s)’) and/or (B) a (serving) base station (beinglocated near the P-UE(s) or (being adjacent to the P-UE(s)) may beconfigured to notify information on the detected ‘SLSS sequence(/ID)’(to the P-UE(s)) (through a pre-configured(/signaled) channel).

Thereafter, based on the above-described information, the UE transmits aV2X message (S1020). Herein, the transmission of the V2X message by theUE based on the above-described information may include determining (ordeciding) a V2X message transmission resource based on theabove-described information and transmitting the V2X message within thedetermined (or decided) transmission resource. Herein, in case anothercommunication is performed within the V2X resource, this may indicatethat the V2X UE switches the transmission resource of the V2X message toa V2X resource other than the above-mentioned V2X resource, and that theUE transmits the V2X message within the switched other V2X resource. TheUE may transmit the V2X message during a predetermined period of timewithin the switched other V2X resource, and the switched V2X resourcemay correspond to a subframe excluding the subframe that was used by theUE in a previous transmission block.

More specifically,

For example, (in case the [Proposed Method #7] (and/or the [ProposedMethod #6]) is applied,) the P-UE(s) may be configured to ‘wake-up’ onlywithin pre-configured(/signaled) ‘sidelink synchronization(/PSBCH)resource(s)’, so as to perform a ‘SLSS (sequence(/ID))(/PSBCH)’detection attempt (and/or to perform a ‘sensing’ operation (fordetecting(/determining) the ‘other communication’) only during (part of)a pre-configured(/signaled) (time(/frequency) resource) section (e.g.,this may be interpreted as a type of ‘partial sensing’ operation)(and/or to perform a ‘sensing’ operation (for detecting(/determining)the ‘other communication’) within a (time(/frequency)) resource(region(/section)) before(/immediately preceding) the resourceselected(/reserved) by the corresponding P-UE(s) for the purpose of V2Xmessage TX (or the transmission operation (time point) of thecorresponding P-UE(s)) (or before a (time(/timing)) offset value that isconfigured(/signaled) in advance from the resource selected(/reserved)by the corresponding P-UE(s) for the purpose of V2X message TX (or thetransmission operation (time point) of the corresponding P-UE(s)))and/or to determine information on an ‘ITS service type(/content)’(currently) being operated (or detected) and/or ‘whether or not theservice correspond to a PS (or non-PS) service’ and/or ‘whether or notanother communication (e.g., ‘DSRC/IEEE 802.11p service’, ‘(othernumerology based) NR eV2X service’) exists’).

Herein, for example, in case the ‘other communication’ is detected, (A)a rule may be defined so that the P-UE(s) can suspend the ‘V2Xcommunication’ (and/or ‘V2X message TX operation’) within the initial(or currently used) pool(/carrier/channel/band) and/or (B) a rule may bedefined so that the P-UE(s) can change a pool(/carrier/channel/band), inwhich the ‘V2X communication’ (and/or the ‘V2X message TX operation’) isperformed, according to a pre-defined(/signaled) rule(/(priority) level)and perform the ‘V2X communication’ (and/or the ‘V2X message TXoperation’) (during a predetermined period of time that isconfigured(/signaled) in advance) within the (corresponding changed)other pool(/carrier/channel/band).

As yet another example, (in case the [Proposed Method #7] (and/or the[Proposed Method #6]) is applied,) when other V2X UE(s) (e.g.,‘V-UE(s)’) being located near the P-UE(s) or (being adjacent to theP-UE(s)) transmit(s)(/report(s)) the determined (or detected)information on an ‘ITS service type(/content)’ (currently) beingoperated (or detected) and/or ‘whether or not the service correspond toa PS (or non-PS) service’ and/or ‘whether or not another communication(e.g., ‘DSRC/IEEE 802.11p service’, ‘(other numerology based) NR eV2Xservice’) exists’ to the (serving) base station, the corresponding otherV2X UE(s) may be configured to report(/transmit) ‘its/their positioninformation’ (and/or ‘position information that has determined thecorresponding information’) (and/or ‘(in case a position-based resourcepool (TDM(/FDM)) division operation is configured(/signaled)) ‘resourcepool(/carrier/channel/band) (index) information in which the ‘othercommunication’ (and/or ‘ITS service’ and/or ‘PS(/non-PS) service’) isdetected’) along with (or in addition to) the above-mentionedinformation.

Herein, for example, the (serving) base station that has received suchinformation may notify the corresponding information to the P-UE(s)(existing within the (reported) adjacent (or identical)position(/region)) (through a pre-defined signal (e.g., (WAN)DL(/PDSCH)). Herein, for example, the (serving) base station that hasreceived the information (from the V-UE(s)) may direct the P-UE(s)existing within the (adjacent or identical) position(/region) (and/orpool(/carrier/channel/band)), wherein the ‘other communication’ isdetected, to perform ‘activation/deactivation’ of the (related) resourcepool and/or to suspend the ‘V2X communication’ (and/or the ‘V2X messageTX operation’) and/or to perform switching to anothercarrier(/channel/band/pool) that is configured(/signaled) in advance(according to a pre-configured(/signaled) rule(/(priority) level).

Herein, as another example, the P-UE(s) that has/have received thecorresponding information (from the (serving) base station) mayconsider(/compare) its/their (current) position (and/or thepool(/carrier/channel/band) in which its/they is/are (currently)performing the V2X message TX operation), and may thendecide(/determine) whether to maintain(/suspend) the V2X message TXoperation within the current pool(/carrier/channel/band) and/or whetheror not to perform switching to another carrier(/channel/band/pool) thatis configured(/signaled) in advance (according to apre-configured(/signaled) rule(/(priority) level) and to perform the‘V2X communication’ (and/or the ‘V2X message TX operation’) within the(corresponding changed (or switched)) other resource(/channel/band)(during a pre-configured(/signaled) period of time). Herein, forexample, in case the above-described rule is applied, the P-UE(s) is/arenot required to (directly) perform the ‘SLSS (sequence(/ID))(/PSBCH)’detection attempt. Herein, for example, the ‘SLSS’ wording may also beinterpreted as ‘PSSS’ (or ‘SSSS’).

As yet another example, when the above-described P-UE(s) of the‘(limited) capability(/chain/circuit)’ format (e.g., the ‘limitedsensing_UE’ format, the ‘type #B_UE’ format, the ‘limited RXchain/circuit’ format (or the ‘no RX chain/circuit’ format or the formatonly having the ‘TX chain/circuit’) perform(s) the ‘partial sensing’operation (during a (time(/frequency) resource) section that isconfigured(/signaled) in advance) for the purpose ofdetecting(/determining) the ‘other communication’ (e.g., ‘DSRC/IEEE802.11p service’, ‘(other numerology based) NR eV2X service’) in orderto reduce the (average) ‘partial sensing’ time (that is required to beperformed until the ‘other communication’ is effectively(/successfully)detected) (or in order to increase the possibility of detecting the‘other communication’ when performing the ‘partial sensing’ operation)settings may be made so that the other (adjacent) V2X UE(s) (e.g.,‘V-UE(s)’) (and/or (serving) base station(/RSU)) can omit the (V2Xcommunication related) channel/signal transmission operation (this maybe interpreted as a type of ‘silencing period’) during a(pre-configured(/signaled)) ‘partial sensing’ (time(/frequency)resource) section.

As yet another example, P-UE(s) (having a limitedreception(/transmission) capability) may be configured(/signaled) withdifferent ‘conditions for (performing) SLSStransmission(/reception(/monitoring))’ depending upon (A) which type(e.g., ‘partial sensing’, ‘full sensing’) of sensing is being performedand/or (B) whether or not random selection (of the transmissionresource) is performed (without performing the sensing operation).

As yet another example, in case of the P-UE(s) (having a limitedreception(/transmission) capability), (part of) the following parametersmay be differently (or independently) configured(/signaled) as comparedto the V-UE(s).

Example #1

When performing transmission resource (re-)reservation(/selection), alimited number of subframes (of a resource reservation (interval) cycleperiod) being assumed(/used) (and/or a C_(reset) value (e.g.,“[10*SL_resource_reselection_counter]”) in Section 2.1. of Table 2 ofthe proposed co-existence method (in the document according to thepresent invention)

Example #2

V2X message priority level (for example, the V2X message may beconfigured(/signaled) to a relatively low (or high) priority level)and/or a “PSSCH-RSRP MEASUREMENT” threshold value in STEP 5 of Section2.3 in Table 2 of the proposed co-existence method (in the documentaccording to the present invention) (and/or a “0.2*M_(total)”, which isrelated coefficient(/ratio) value in STEP 6(/8) of Section 2.3 in Table2 of the proposed co-existence method (in the document according to thepresent invention) (for example, this may be interpreted as a ratiovalue drawing(/determining) a minimum number of (candidate) resourcesthat should be remaining (within set SA) (among the entire (candidate)resources) after performing STEP 5 of Section 2.3 in Table 2 of theproposed co-existence method (in the document according to the presentinvention) and/or a ratio value drawing(/determining) a (minimum) numberof (candidate) resources that should exist within set SB afterperforming STEP 8 of Section 2.3 in Table 2 of the proposed co-existencemethod (in the document according to the present invention)) may beconfigured(/signaled) a different (or independent) values, and/or anincreasing value of “PSSCH-RSRP MEASUREMENT” (e.g., “3DB”) being appliedto a case where the minimum number of (candidate) resources that shouldremain within set S_(A) (among the entire (candidate) resources) afterperforming STEP 5 of Section 2.3 in Table 2 of the proposed co-existencemethod (in the document according to the present invention), and/or acycle period value being used in a sensing operation (e.g., STEP 5 ofSection 2.3 in Table 2 of the proposed co-existence method (in thedocument according to the present invention)) (and/or an energymeasurement operation (e.g., STEP 7/8 of Section 2.3 in Table 2 of theproposed co-existence method (in the document according to the presentinvention)). Herein, for example, (i.e.,) the above-described examplemay be applied to the operation in which the network signals the(partial) sensing pattern of the P-UE.

Example #3

I_VALUE (range) value and/or P_STEP value that can be selected(/allowed)within a V2X resource pool (and/or (V2X) carrier).

Example #4

Transmission power related (open-loop) parameter(/value) (e.g., “Po”,“ALPHA”, and so on) and/or V2X resource pool(/carrier).

As another example, as shown below in Table 6, a ‘V2X messagetransmission operation’ (and/or ‘(transmission) resourceselection(/reservation) operation’) of the P-UE(s) (having a limitedreception (RX)(/transmission (TX)) capability) may be efficientlysupported.

TABLE 6 4. Example of efficiently supporting a ‘V2X message)transmission operation’ (and/or ‘(transmission) resourceselection(/reservation) operation’) of the P-UE(s) (having a limitedreception (RX)(/transmission (TX)) capability) 4.1. Prerequisites for arandom resource selection corresponding to P-UE According to the presentinvention, the P-UEs including all P-UEs having no sidelink Rxcapability may support all possibilities for being capable of usingrandom selection. In case a P-UE uses random selection, only the pool,wherein the random selection performed by the P-UE is allowed, may beused for the random selection. Whether or not the pool, wherein therandom selection performed by the P- UE is allowed, is allowed tooverlap with another pool may depend upon the network configuration. Apossibility of configuring pools, wherein the random selection performedby the P-UE is not allowed, may be supported. According to the presentinvention, the possibility of the P-UE being capable of using partialsensing in a sub-set of a subframe is supported. The partial sensing ofthe P-UE may be based on a V2V sensing based resource selection. At thispoint, the resource selection of the P-UE according to the partialsensing may be similar to the V2V sensing based resource selection. Incase of a P-UE having a sidelink Rx function, it may be consideredwhether or not the partial sensing support is necessary (or mandatory).4.2. Method for supporting random resource selection in a V2P Thecurrent sidelink transmission mode 4 is based on sensing and resourcereservation (i.e., using the same time/frequency resource for a numberof transmission block (TB) transmissions). Since the random resourceselection of the P-UE will skip the sensing procedure, whether or notthe randomly selected resource will be maintained for a specific periodof time may have to be considered. Applying a reservation operation tothe random resource selection may have the following advantages anddisadvantages as described below. Advantages: Even though the P-UE doesnot perform sensing, a resource that is reserved by the P-UE may bemonitored by the V-UE, and collision may be avoided during the resourceselection of the V-UE. Disadvantages: Firstly, in case the P-UE selectsa non-preferable resource (e.g., resource being used by another adjacentUE or resource experiencing intense in-band emission interference fromanother UE transmission), as degradation in the performance isprolonged, this may lead to consecutive failures in message delivery.The advantage and disadvantage of applying resource reservation to therandom selection may depend upon whether or not the P-UE transmissionand the V-UE transmission share the same pool. In case the resourcepool, wherein the random selection is allowed, does not overlap with theresource pool that is used for the V-UE transmission, since there is noUE benefiting from the operation of resource reservation, there may beno advantage in applying resource reservation. Accordingly, randomselection having no resource reservation should be supported in thepresent invention. This indicates that whether or not the randomselection through the resource reservation is required to beadditionally supported should be considered. Proposal 1: At least arandom selection having no resource reservation may be supported in thepresent invention. This indicates that whether or not the randomselection through the resource reservation is required to beadditionally supported should be considered. Additionally, in the randomresource selection procedure, how the resource re-selection is performedshould also be considered. In order to avoid consistently selectinginappropriate resources, when the P-UE re-selects a resource, changingthe resource (i.e., avoiding re-selection of the resource that hasalready been selected and selecting other resources) is needed. Morespecifically, the P-UE may exclude the subframe that has already beenused in a previous transmission block (TB) transmission. And,accordingly, the influence of the in-band emission may be randomized bythe TB transmission. Proposal 2: The P-UE may exclude the subframe thathas already been used in a previous transmission block (TB)transmission. And, accordingly, the influence of the in-band emissionmay be randomized by the TB transmission. The transmission capability ofthe P-UE may also be considered. Since the P-UE may transmit one messageper second, the usage rate of a transmission chain in a PC5 carrier forV2P may be equal to 0.2%. Therefore, in case all P-UEs are required tobe equipped with a V2P transmission dedicated transmission chain, thedevice implementation cost may increase unnecessarily. Being similar tothe 3gpp Rel-12/13 D2D, by using a ProSe gap for the P-UE transmission,a chain being used for the UL transmission may be temporarily borrowed.Proposal 3: The P-UE may temporarily perform switching of thetransmission chain being used for the UL transmission with an SLtransmission chain for V2P. 4.3. Conclusion The above-describedproposals may be summarized as described below. Proposal 1: At least arandom selection having no resource reservation may be supported in thepresent invention. This indicates that whether or not the randomselection through the resource reservation is required to beadditionally supported should be considered. Proposal 2: The P-UE mayexclude the subframe that has already been used in a previoustransmission block (TB) transmission. And, accordingly, the influence ofthe in-band emission may be randomized by the TB transmission. Proposal3: The P-UE may temporarily perform switching of the transmission chainbeing used for the UL transmission with an SL transmission chain forV2P.

Hereinafter, in order to facilitate the understanding, theabove-described exemplary embodiment will be described below withreference to the flow chart. Hereinafter, for simplicity in thedescription, details of the following drawing that overlap with thedetails described above will be omitted. In other words, theabove-described exemplary embodiments may also be applied to theexemplary embodiments that will hereinafter be described.

FIG. 19 is a flow chart showing a method for transmitting a V2X messageperformed by a UE having a limited reception capability according toanother exemplary embodiment of the present invention.

According to FIG. 19, the UE may receive information indicating thatanother communication is being performed(/detected) within a Vehicle toX (V2X) carrier from another V2X UE (S1110). At this point, as describedabove, the other V2X UE may correspond to a V-UE.

For example, as described above, the step of receiving informationindicating that another communication is being performed(/detected)within a Vehicle to X (V2X) carrier may indicate that, as describedabove, an ‘ITS service type(/content)’ (currently) being operated (ordetected) and/or ‘whether or not the service correspond to a PS (ornon-PS) service’ (and/or ‘whether or not another communication (e.g.,‘DSRC/IEEE 802.11p service’, ‘(other numerology based) NR eV2X service’)exists’), and so on, is/are notified (to the P-UE(s)) (through apre-configured(/signaled) channel). Since a detailed description of thisexample has already been presented above, a detailed description of thesame will be omitted for simplicity.

Thereafter, based on the above-described information, the UE maydetermine a transmission resource of a V2X message (S1120).

Herein, for example, based on the above-described information, in casethe ‘other communication’ is detected, (A) a rule may be defined so thatthe P-UE(s) can suspend the ‘V2X communication’ (and/or ‘V2X message TXoperation’) within the initial (or currently used)pool(/carrier/channel/band) and/or (B) a rule may be defined so that theP-UE(s) can change a pool(/carrier/channel/band), in which the ‘V2Xcommunication’ (and/or the ‘V2X message TX operation’) is performed,according to a pre-defined(/signaled) rule(/(priority) level) andperform the ‘V2X communication’ (and/or the ‘V2X message TX operation’)(during a predetermined period of time that is configured(/signaled) inadvance) within the (corresponding changed) otherpool(/carrier/channel/band). Since a detailed description of thisexample has already been presented above, a detailed description of thesame will be omitted for simplicity.

Additionally, for example, in case of the above-described P-UE(s)(having a limited reception(/transmission) capability), (part of) theparameters may be differently (or independently) configured(/signaled)as compared to the V-UE(s). Since a detailed description of this examplehas already been presented above, a detailed description of the samewill be omitted for simplicity.

Additionally, for example, a ‘V2X message transmission operation’(and/or ‘(transmission) resource selection(/reservation) operation’) ofthe P-UE(s) (having a limited reception (RX)(/transmission (TX))capability) may be efficiently supported. Since a detailed descriptionof this example has already been presented above, a detailed descriptionof the same will be omitted for simplicity.

Thereafter, within the determined transmission resource, the UE maytransmit the V2X message (S1130). The example of the UE transmitting theV2X message within the determined transmission resource has already beendescribed above in detail.

FIG. 20 is a flow chart showing a method for transmitting a V2X messageperformed by a UE having a limited reception capability according to yetanother exemplary embodiment of the present invention.

According to FIG. 20, the base station may receive informationindicating that another communication is being performed(/detected)within a Vehicle to X (V2X) carrier from a V2X UE (other than a P-UE)(S1210). At this point, as described above, the other V2X UE maycorrespond to a V-UE.

For example, as described above, the step of receiving informationindicating that another communication is being performed(/detected)within a Vehicle to X (V2X) carrier may indicate that, as describedabove, an ‘ITS service type(/content)’ (currently) being operated (ordetected) and/or ‘whether or not the service correspond to a PS (ornon-PS) service’ (and/or ‘whether or not another communication (e.g.,‘DSRC/IEEE 802.11p service’, ‘(other numerology based) NR eV2X service’)exists’), and so on, is/are notified (to the P-UE(s)) (through apre-configured(/signaled) channel). Since a detailed description of thisexample has already been presented above, a detailed description of thesame will be omitted for simplicity.

Additionally, for example, when other V2X UE(s) (e.g., ‘V-UE(s)’) beinglocated near the P-UE(s) or (being adjacent to the P-UE(s))transmit(s)(/report(s)) the determined (or detected) information on an‘ITS service type(/content)’ (currently) being operated (or detected)and/or ‘whether or not the service correspond to a PS (or non-PS)service’ and/or ‘whether or not another communication (e.g., ‘DSRC/IEEE802.11p service’, ‘(other numerology based) NR eV2X service’) exists' tothe (serving) base station, the corresponding other V2X UE(s) may beconfigured to report(/transmit) ‘its/their position information’ (and/or‘position information that has determined the correspondinginformation’) (and/or ‘(in case a position-based resource pool(TDM(/FDM)) division operation is configured(/signaled)) ‘resourcepool(/carrier/channel/band) (index) information in which the ‘othercommunication’ (and/or ‘ITS service’ and/or ‘PS(/non-PS) service’) isdetected’) along with (or in addition to) the above-mentionedinformation. Since a detailed description of this example has alreadybeen presented above, a detailed description of the same will be omittedfor simplicity.

The UE (a UE other than the other V2X UE, e.g., P-UE) may receiveinformation indicating that another communication is beingperformed(/detected) within a Vehicle to X (V2X) carrier from the basestation (S1220). More specifically, the UE may receive the informationindicating that another communication is being performed(/detected)within the Vehicle to X (V2X) carrier, which is transmitted by the otherV2X UE and, then, forwarded by the base station. Alternatively, the UEmay receive the information indicating that another communication isbeing performed(/detected) within the Vehicle to X (V2X) carrier, whichis generated by the base station.

For example, as described above, the step of receiving informationindicating that another communication is being performed(/detected)within a Vehicle to X (V2X) carrier may indicate that, as describedabove, an ‘ITS service type(/content)’ (currently) being operated (ordetected) and/or ‘whether or not the service correspond to a PS (ornon-PS) service’ (and/or ‘whether or not another communication (e.g.,‘DSRC/IEEE 802.11p service’, ‘(other numerology based) NR eV2X service’)exists’), and so on, is/are notified (to the P-UE(s)) (through apre-configured(/signaled) channel). Since a detailed description of thisexample has already been presented above, a detailed description of thesame will be omitted for simplicity.

Thereafter, based on the above-described information, the UE maydetermine a transmission resource of a V2X message (S1230).

Herein, for example, based on the above-described information, in casethe ‘other communication’ is detected, (A) a rule may be defined so thatthe P-UE(s) can suspend the ‘V2X communication’ (and/or ‘V2X message TXoperation’) within the initial (or currently used)pool(/carrier/channel/band) and/or (B) a rule may be defined so that theP-UE(s) can change a pool(/carrier/channel/band), in which the ‘V2Xcommunication’ (and/or the ‘V2X message TX operation’) is performed,according to a pre-defined(/signaled) rule(/(priority) level) andperform the ‘V2X communication’ (and/or the ‘V2X message TX operation’)(during a predetermined period of time that is configured(/signaled) inadvance) within the (corresponding changed) otherpool(/carrier/channel/band). Since a detailed description of thisexample has already been presented above, a detailed description of thesame will be omitted for simplicity.

Additionally, for example, in case of the above-described P-UE(s)(having a limited reception(/transmission) capability), (part of) theparameters may be differently (or independently) configured(/signaled)as compared to the V-UE(s). Since a detailed description of this examplehas already been presented above, a detailed description of the samewill be omitted for simplicity.

Additionally, for example, a ‘V2X message transmission operation’(and/or ‘(transmission) resource selection(/reservation) operation’) ofthe P-UE(s) (having a limited reception (RX)(/transmission (TX))capability) may be efficiently supported. Since a detailed descriptionof this example has already been presented above, a detailed descriptionof the same will be omitted for simplicity.

Thereafter, within the determined transmission resource, the UE maytransmit the V2X message (S1240). The example of the UE transmitting theV2X message within the determined transmission resource has already beendescribed above in detail.

In case of a PS service related V2X transmission performed by a V2X UE(moving at a relatively fast speed), the WAN transmission operation maynot always be prioritized over the V2X transmission operation.

Accordingly, in the present invention, in case the WAN transmissionoperation overlaps with the V2X transmission operation in the timedomain, how the V2X transmission operation will be performed by usingwhich method will hereinafter be described in detail with reference tothe corresponding drawings.

FIG. 21 is a flow chart of a V2X transmission method, in a case where aWAN transmission operation overlaps with a V2X transmission operation ina time domain, according to an exemplary embodiment of the presentinvention.

According to FIG. 21, in case the WAN transmission operation overlapswith the V2X transmission operation in the time domain, the UE maydetermine whether or not the WAN transmission operation and the V2Xtransmission operation are performed within the same carrier (S1310). Atthis point, the UE may correspond to the above-described V2X UE.

Thereafter, based on the determined result, the UE may perform the V2Xtransmission operation (S1320). More specifically, (A) a method ofefficiently determining the V2X transmission power, in case the V2Xtransmission operation and the WAN (UL) transmission operation eachbeing performed within a different carrier (partially or fully) overlapone another in the time domain and/or (B) a detailed method ofprioritizing the V2X transmission operation (overlapping with the WAN(UL) transmission operation within the same carrier (and/or differentcarriers) in the time domain) over the WAN (UL) transmission, themethod(s) being performed by the UE, will hereinafter be described indetail.

(A) A method of efficiently determining the V2X transmission power, incase the V2X transmission operation and the WAN (UL) transmissionoperation each being performed within a different carrier (partially orfully) overlap one another in the time domain

FIG. 22 shows a general example, wherein the V2X transmission operationand the WAN (UL) transmission operation each being performed within adifferent carrier (partially or fully) overlap one another in the timedomain.

As shown in FIG. 22, the UE may perform the V2X transmission at a tOtime point within a V2X carrier having an f0 frequency, and the UE mayperform the WAN transmission at a tO time point within a WAN carrierhaving an f1 frequency.

In the subframe, in case a sidelink transmission of the UE overlaps withan uplink transmission of the UE in the aspect of time, the UE isrequired to adjust the sidelink transmission power so that the totaltransmission power does not exceed PCMAX in the overlapping part.

Generally, according to the D2D operation, in case the WAN TX and the SLTX overlap one another in different carriers in the aspect of time, theWAN TX may be prioritized over the SL TX in the aspect of powerassignment.

In other words, in case the D2D operations are performed withindifferent carriers, and in case the WAN TX and the SL TX are performedat the same time point or at overlapping time points, the UE may assigna larger level of power to the WAN TX (as compared to the SL TX).However, as described above, in case of the V2X transmission that isperformed by a V2X UE, which moves at a relatively faster speed, sincethe V2X transmission more frequently requires more urgent transmissionoperations as compared to the D2D transmission, the WAN transmissionoperation may not be prioritized over the V2X transmission operation.

Accordingly, in order to resolve this problem, the following exemplaryembodiment may be provided.

FIG. 23 is a flow chart of a V2X transmission method, in a case where aWAN transmission operation overlaps with a V2X transmission operation ina time domain, according to another exemplary embodiment of the presentinvention.

According to FIG. 23, in case the WAN transmission operation overlapswith the V2X transmission operation in the time domain, and in case theV2X transmission operation and the WAN transmission operation are eachperformed within a different carrier, the transmission power beingapplied to the V2X transmission operation may be determined (S1410). TheUE may refer to a V2X UE. More specifically, the following options maybe provided.

In case the following options are applied, when assigning the power, byassigning a higher priority level to the V2X TX (over the WAN TX), adegradation in the V2V performance may be efficiently prevented.

At this point, for example, in case a V2V TX occurs in a time domainthat is configured along with a ‘V2V gap’, or in case a V2V TX having aProSe priority per packet (PPPP) (pre-)configured therein is performed,the options listed below may be limitedly applied. According to Option 2presented below, solutions (or procedures) being related to a dualconnection may be re-used.

Option 1: Power is first assigned to the V2V TX, and the remaining poweris assigned to the WAN TX.

Option 2: Minimum power for the V2V TX is ensured.

Herein, for example, a V2X message TX (partially and/or fully) overlapswith a WAN UL TX in the time domain, within different carriers (orfrequencies) (and/or the same carrier (or frequency)) (in the point ofview of a (one) specific V2X UE), (part of) the following rule may beapplied so that the performance of the V2X message TX (having arelatively high PPPP) and/or the WAN UL TX (being relatively moreimportant) (e.g., PUCCH(/PRACH)(/PUSCH/SRS)) can be guaranteed (orensured) (at a maximum level).

Herein, for example, (part of) the following rule may be limitedlyapplied only in a case where a (time) synchronization difference betweenthe V2X message TX and the WAN UL TX is greater than apre-configured(/signaled) threshold value.

Example #1

A “guaranteed minimum power (G_minpower))” may be configured(/signaled)in the V2X message TX (having a value that is greater than or equal to apre-configured(/signaled) PPPP threshold value) and/or the WAN UL TX (ofa pre-configured(/signaled) channel(/signal)).

Herein, for example, the process of applying thepre-configured(/signaled) G_minpower value within the WAN UL TX (and/orV2X message TX) may be limitedly performed only in a case where a ProSepriority per packet (PPPP) value of the V2X message TX that (partiallyor fully) overlaps (in the time domain) is greater than thepre-configured(/signaled) threshold value (for example, in case the PPPPvalue of the V2X message TX is smaller than thepre-configured(/signaled) threshold value, the power assignment to theWAN UL TX may be prioritized) (and/or a case where a sum of the(required) V2X message TX power value and the required WAN UL TX powervalue exceeds a maximum transmission power value (e.g., ‘23 DBM’) of theUE).

Herein, for example, the WAN UL TX (and/or V2X message TX) relatedG_minpower value may be differently (or independently)configured(/signaled) for each PPPP value of the V2X message TX (being(partially or fully) overlapped (in the domain)).

Example #2

In case the PPPP value of the overlapping V2X message TX (being(partially or fully) overlapped) (in the domain) is greater than thepre-configured(/signaled) threshold value, settings may be made so thatthe WAN UL TX can be omitted (for example, in case the PPPP value of theV2X message TX is smaller than the pre-configured(/signaled) thresholdvalue, the V2X message TX may be omitted).

Herein, for example, the corresponding rule may be limitedly appliedonly in a case of performing WAN UL TX after excluding apre-configured(/signaled) (important) channel(/signal) (e.g.,PUCCH(/PRACH)(/PUSCH/SRS)).

Herein, for example, in case of the pre-configured(/signaled)(important) channel(/signal) (e.g., PUCCH(/PRACH)(/PUSCH/SRS)), theabove-described (Example #1) (e.g., G_minpower) may be (exceptionally)applied (for example, this may be interpreted that settings are made sothat the (corresponding) (important) channel(/signal) transmission isnot omitted) and/or the V2X message TX may be (exceptionally) omitted.

The above-described details may be summarized as shown below.

-   -   Proposal: In summary, the two options listed below may support a        prioritized power assignment to the SL TX over the WAN TX.

(1) Option 1: Power is first assigned to the V2V TX, and the remainingpower is assigned to the WAN TX.

(2) Option 2: Minimum power for the V2V TX is ensured.

(B) A detailed method of prioritizing the V2X transmission operation(overlapping with the WAN (UL) transmission operation within the samecarrier (and/or different carriers) in the time domain) over the WAN(UL) transmission

FIG. 24 shows a general example, wherein the V2X transmission operation(overlapping with the WAN (UL) transmission operation within the samecarrier (and/or different carriers) in the time domain) is prioritizedover the WAN (UL) transmission.

As shown in FIG. 24, the UE may perform the V2X transmission and WANtransmission at a tO time point within the same carrier having an f0frequency. Although FIG. 24 generally shows an example of performing theV2X transmission and the WAN transmission within the same carrier forsimplicity in the description, the following exemplary embodiment of thepresent invention may also be applied to a case where the V2Xtransmission and the WAN transmission are performed within differentcarriers.

Herein, for the above-described PC5-based V2V and WAN co-existence, thefollowing details may be supported.

Firstly, a sidelink open-loop power control may be re-used for the SL TXrelated to V2V.

Additionally, the SL TX for V2V may be prioritized over the WAN TX. Atthis point, the SL TX related to V2V may also apply the above-describedD2D operations (e.g., Mode 1 and/o Mode 2). Herein, the priority levelmay be managed by the base station (eNB).

Moreover, the same receiver function of the D2D communication UE may beassumed in the V2V UE. More specifically, in case the UE is configuredto receive V2V, the RX chain may be capable of always receiving the V2Vsignal without influencing the WAN reception.

Hereinafter, in case the WAN transmission operation overlaps with theV2X transmission operation in the time domain, the V2X transmissionmethod will be described in more detail.

FIG. 25 is a flow chart of a V2X transmission method, in a case where aWAN transmission operation overlaps with a V2X transmission operation ina time domain, according to yet another exemplary embodiment of thepresent invention.

According to FIG. 25, in case the WAN transmission operation overlapswith the V2X transmission operation in the time domain, and in case theV2X transmission operation and the WAN transmission operation areperformed within the same carrier, the UE may determine the prioritylevel of the V2X transmission operation (S1510). At this point, the UEmay correspond to the above-described V2X UE. More specifically, thefollowing options may be applied.

It is important for the SL TX prioritization through the WAN TX toensure (or guarantee) the V2V performance of the TM4 in a shared carriercase (i.e., SL TX and WAN TX within the same carrier). As one of thepossible options supporting this function, the re-usage of a ‘ProSe gap’(e.g., a time section during which the D2D TX being configured by thenetwork is prioritized over the WAN TX) may be considered along with anoptimized additional correction for a V2V traffic pattern.

As another example, it may be considered to always prioritize the V2V TXhaving the PPPP configured therein over the WAN TX. In other words, incase the V2V TX overlaps with the WAN TX within the same carrier in theaspect of time, the V2V TX having another PPPP may be dropped.

Proposal: In order to support the prioritization of the SL TX throughthe WAN TX, one of the following options may be selected.

Option 1: After applying a number of required corrections (e.g.:adoption of an additional cycle period being adequate for the V2Vtraffic pattern), a ‘ProSe gap’ that is related to Rel-13 eD2D searchmay be re-used. Herein, for example, in the correspond GAP((time(/frequency)) resource) region, settings may be made so that onlythe V2X (message) TX, which is interconnected with a PPPP being equal toor greater than a pre-configured(/signaled) PPPP (or a specific PPPPthat is pre-configured(/signaled), may be prioritized over the WAN ULTX.

Option 2: A V2V TX having a (pre-)configured PPPP may also beprioritized over the WAN TX.

In conclusion, the above-described details may be summarized asdescribed below.

-   -   Proposal: In order to support the prioritization of the SL TX        through the WAN TX, one of the following options may be        selected.

(1) Option 1: After applying a number of required corrections (e.g.:adoption of an additional cycle period being adequate for the V2Vtraffic pattern), a ‘ProSe gap’ that is related to Rel-13 eD2D searchmay be re-used.

(2) Option 2: A V2V TX having a (pre-)configured PPPP may also beprioritized over the WAN TX.

As another example, in case of the P-UE(S), for theselection(/switching) operation between a “(partial) sensing-basedresource selection behaviour(/pool)” and a “random resource selectionbehaviour(/pool)”, its (final) performance or non-performance may bedetermined in accordance with whether or not the “congestion level”(which is (directly) measured by the P-UE(s), or which is received fromanother V2X entity (e.g., the (serving) base station, V-UE(s)) exceedsthe pre-configured(/signaled) threshold value.

Herein, if the “congestion level” (which is (directly) measured by theP-UE(s) that has/have performed(/used) the “(partial) sensing-basedresource selection behaviour(/pool)”, or which is received from anotherV2X entity) exceeds the pre-configured(/signaled) threshold value,settings may be made so that the “random resource selectionbehaviour(/pool)” can be performed(/used).

Since the examples of the above-described proposed methods may beincluded as one of the implementation methods of the present invention,it will be apparent that the corresponding examples can be viewed (orconsidered) as a type of the proposed methods. Additionally, althoughthe above-described proposed methods may be independently implemented,the above-described proposed methods may also be implemented in acombined (or integrated) form of parts of the proposed methods.

For example, although the present invention is described based on a 3GPPLTE system for simplicity in the description, the scope of systems inwhich the proposed methods can be applied may be extended to diversesystems other than the 3GPP LTE system.

For example, the proposed methods according to the present invention mayalso be extendedly applied to D2D communication. Herein, for example,D2D communication refers to performing communication between a UE andanother UE by using a direct wireless channel. And, herein, for example,although the UE refers to a user device, in case a network equipment,such as a base station, transmits/receives signals according to acommunication method performed between UEs, the corresponding networkequipment may also be viewed as a type of UE.

Additionally, for example, the proposed methods according to the presentinvention may also be limitedly applied only in MODE 2 V2X operations(and/or MODE 1 V2X operations).

Additionally, for example, in addition to being applied to P-UE(s)having limited reception(/transmission) chain/circuit capability, theproposed methods according to the present invention may also beextendedly applied to vehicle UE(s) (V-UE(s)) (and/or P-UE(s) havingnon-limited reception(/transmission) chain/circuit capability).

Additionally, for example, the proposed methods according to the presentinvention may also be extendedly applied to a case where the WAN UL TXand the V2X message TX overlap with one another in different carrier(s)within the time domain.

Additionally, for example, the proposed methods according to the presentinvention may also be extendedly applied to a case where the P-UE(s)(having limited reception(/transmission) chain/circuit capability)perform(s) a “partial sensing operation” (corresponding to (part of) theresource section(/region)) within the “sensing gap(/resource) (or RXgap(/resource) or partial sensing gap(/resource)”, which is receivedfrom the network (or base station) and/or a case where the P-UE(s)perform the “partial sensing operation” within (part of) the resourcesection(/region), which the P-UE(s) has/have configured(/signaled) (onits/their own), without receiving any of the corresponding relatedinformation.

Additionally, for example, the proposed methods according to the presentinvention may be limitedly applied only to a case where the P-UE(s)(having limited reception(/transmission) chain/circuit capability)perform(s) a ‘partial sensing’ (and/or ‘full sensing’) operation (basedtransmission resource selection) (and/or a case where the P-UE(s)(having limited reception(/transmission) chain/circuit capability)perform(s) transmission resource random selection (without performingany sensing operation).

Additionally, for example, the proposed methods according to the presentinvention may be limitedly applied only to a case where the V2X MESSAGETX and the WAN UL TX (partially and/or fully) overlap with one anotherin the time domain within different carriers (or frequencies) (and/orthe same carrier (or frequency) (in the point of view of a specific(one) V2X UE).

FIG. 26 is a block diagram showing a user equipment (UE) implementing anexemplary embodiment of the present invention.

Referring to FIG. 26, a user equipment (UE) (1100) includes a processor(1110), a memory (1120), and a radio frequency (RF) unit (1130).

According to an exemplary embodiment of the present invention, theprocessor (1110) may execute the functions/operations/methods that aredescribed in the present invention. For example, the processor (1110)may receive type information indicating a type of the resource pool,and, then, based on the type information, the processor (1110) mayperform at least any one of random selection and partial sensing basedrandom selection in the corresponding resource pool.

In case the type of the resource pool corresponds to the type whereinonly the partial sensing based resource selection is allowed to beperformed, the processor (1110) may semi-persistently reserve theresource that is selected by using the partial sensing based resourceselection.

In case the type of the resource pool corresponds to the type whereinonly the random selection is allowed to be performed, the processor(1110) may not semi-persistently reserve the resource that is selectedby the random selection.

In case the type of the resource pool corresponds to the type whereinthe partial sensing based resource selection is allowed to be performed,however, if the processor (1110) performs random selection in thecorresponding resource pool, the processor (1110) may semi-persistentlyreserve the randomly selected resource. The resource beingsemi-persistently reserved has already been described above in detailwith reference to FIG. 17.

The RF unit 1130 is connected to the processor 1110 to transmit andreceive radio signals.

The processor may comprise an application-specific integrated circuit(ASIC), other chipset, logic circuitry and/or data processing device.The memory may include read-only memory (ROM), random access memory(RAM), flash memory, memory cards, storage media, and/or other storagedevices. The RF unit may include a baseband circuit for processing theradio signal. When the embodiment is implemented in software, theabove-described techniques may be implemented with modules (processes,functions, and so on) that perform the functions described above. Themodule may be stored in the memory and may be executed by the processor.The memory may be internal or external to the processor, and may becoupled to the processor by various well known means.

What is claimed is:
 1. A method for selecting a sidelink transmissionresource in a wireless communication system, the method performed by auser equipment (UE) and comprising: receiving type information informingat least one resource selection mechanism for a resource pool; andperforming a resource selection by one resource selection mechanism,among a random selection and a partial sensing, in the resource poolbased on the type information, wherein the type information informswhether the partial sensing is allowed for the UE selecting a resourcein the resource pool, and whether the random selection is allowed forthe UE selecting a resource in the resource pool.
 2. The method of claim1, wherein the partial sensing is a resource selection mechanism thatthe UE senses only some subframes, among subframes in a sensing window,and selects a specific subframe in a selection window as a sidelinktransmission subframe based on the sensing result.
 3. The method ofclaim 2, wherein the sensing window comprises 1,000 consecutivesubframes, and wherein the selecting window comprises 100 consecutivesubframes located after the sensing window.
 4. The method of claim 1,wherein, in response to the partial sensing is allowed in the resourcepool, the UE semi-persistently reserves resources selected based on thepartial sensing.
 5. The method of claim 1, wherein, in response to onlythe random selection is allowed in the resource pool, the UE does notsemi-persistently reserve resources selected based on the randomselection.
 6. The method of claim 1, wherein, in response to the partialsensing is allowed in the resource pool and in response to the UEperforms the random selection in the resource pool, the UEsemi-persistently reserves the randomly selected resources.
 7. Themethod of claim 1, wherein the UE is a UE communicating with another UEthat operates in a vehicle.
 8. A user equipment (UE), comprising: atransceiver; at least one processor; and at least one computer memoryoperatively connected to the at least one processor and storinginstructions that, based on being executed by the at least oneprocessor, perform operations comprising: receiving, via thetransceiver, type information informing at least one resource selectionmechanism for a resource pool, and performing a resource selection byone resource selection mechanism, among a random selection and a partialsensing, in the resource pool based on the type information, wherein thetype information informs whether the partial sensing is allowed for theUE selecting a resource in the resource pool, and whether the randomselection is allowed for the UE selecting a resource in the resourcepool.
 9. The user equipment of claim 8, wherein the partial sensing is aresource selection mechanism that the UE senses only some subframes,among subframes in a sensing window, and selects a specific subframe ina selection window as a sidelink transmission subframe based on thesensing result.
 10. The user equipment of claim 9, wherein the sensingwindow comprises 1,000 consecutive subframes, and wherein the selectingwindow comprises 100 consecutive subframes located after the sensingwindow.
 11. The user equipment of claim 8, wherein, in response to thepartial sensing is allowed in the resource pool, the UEsemi-persistently reserves resources selected based on the partialsensing.
 12. The user equipment of claim 8, wherein, in response to onlythe random selection is allowed in the resource pool, the UE does notsemi-persistently reserve resources selected based on the randomselection.
 13. The user equipment of claim 8, wherein in response to thepartial sensing is allowed in the resource pool and in response to theUE performs the random selection in the resource pool, the UEsemi-persistently reserves the randomly selected resources.